JP6910702B2 - Optical glass, preform materials and optical elements - Google Patents

Description

The present invention relates to optical glass, preform materials and optical elements.

In recent years, the digitization and high definition of devices that use optical systems have been rapidly advancing, and various optical devices such as imaging 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 for reducing the number of optical elements such as lenses and prisms used in an optical system, and reducing the weight and size of the entire optical system.

_{Among the optical glasses for which optical elements are manufactured, it has a refractive index (nd} ) of 1.75 or more and 1.88 or less, which can reduce the weight and size of the entire optical system, and is 35 or more and 45 or less. The demand for high-refractive-index, low-dispersion glass having the Abbe number (ν _{d) is very high.} As such a high refractive index low dispersion glass, glass compositions such as those represented by Patent Documents 1 to 3 are known.

Japanese Unexamined Patent Publication No. 2014-073962 JP-A-2009-298646 Japanese Unexamined Patent Publication No. 2006-240888

In order to reduce the material cost of the optical glass, it is desired that the raw material cost of various components constituting the optical glass is as low as possible. However, the glass compositions described in Patent Documents 1 to ₃ use expensive raw materials such as _{Ta 2} O ₅ and Gd ₂ O 3 in order to realize a high refractive index, and these requirements are met. It is hard to say that it will respond sufficiently.

If other inexpensive raw materials are used to reduce the amount of expensive raw materials used, it is difficult to achieve high refractive index and low dispersion, and in order to achieve this, a large amount of relatively inexpensive rare earth components are used. It must be added and tends to have poor devitrification. Even when the material cost of the optical glass is reduced, the optical glass is required to have high stability and to be resistant to devitrification.

Further, the lenses used in the optical system include a spherical lens and an aspherical lens, and if the aspherical lens is used, the number of optical elements can be reduced. As a method for manufacturing an aspherical lens, a method of obtaining the shape of an optical element by pressure molding a gob or preform at a high temperature using an ultra-precision machined mold (precision molding) has become the mainstream. There is. In this method, it is required to lower the glass transition point of the glass preform in order to prevent damage to the molding die itself and the release film installed on the inner surface of the molding die during press molding. ..

The present invention has been made in view of the above problems, and an object of the present invention is to _{have high stability while the refractive index (nd} ) and Abbe number (ν _d ) are within desired ranges. The purpose is to obtain glass at a lower cost. In addition, it is preferable that the material is capable of precision molding.

As a result of intensive test and research to solve the above problems, the present inventors have reduced the content of high material cost components, particularly Ta ₂ O ₅ component and Gd ₂ O ₃ component, while reducing B. It has been found that a glass having a high refractive index and low dispersion and high stability can be obtained by adjusting the addition amounts of the ₂ O ₃ component, the La ₂ O _{3 component and the Zn O component.} In addition, by adding a large amount of ZnO, it is possible to lower the glass transition point, and it has been found that the glass material is easy to perform precision mold press molding, and the present invention has been completed.
Specifically, the present invention provides the following.

(1) By mass% of oxide equivalent composition,
B ₂ O ₃ component 10.0-40.0%,
La ₂ O ₃ component 15.0-50.0%
ZnO component 10.0-45.0%
And
The mass sum (La ₂ O ₃ + Y ₂ O ₃ + ZnO) based on the oxide is 30.0 to 80.0%.
Refractive index _{(n d)} is 1.75 to 1.88, the optical glass of the Abbe number ([nu _d) is characterized in that 35 to 45.

(2) By mass% of oxide equivalent composition,
SiO ₂ component 0 to 15.0%,
ZrO ₂ component 0 to 15.0%
Nb ₂ O ₅ component 0 to 20.0%
WO ₃ component 0-20.0%
The optical glass according to (1).

(3) By mass% of oxide equivalent composition,
Y ₂ O ₃ component 0 to 20.0%
Gd ₂ O ₃ component 0 to 20.0%
Yb ₂ O ₃ component 0 to 20.0%
MgO component 0 to 15.0%
CaO component 0 to 15.0%
SrO component 0 to 15.0%
BaO component 0-20.0%
Li ₂ O component 0 to 10.0%
Na ₂ O component 0-5.0%
K ₂ O component 0-5.0%
TiO ₂ component 0 to 10.0%
Bi ₂ O ₃ component 0 to 10.0%
P ₂ O ₅ component 0 to 10.0%
Ta ₂ O ₅ component 0 to 10.0%
Al ₂ O ₃ component 0 to 10.0%
Ga ₂ O ₃ component 0 to 10.0%
GeO ₂ component 0-10.0%
TeO ₂ component 0 to 15.0%
SnO ₂ component 0-3.0%
Sb ₂ O ₃ component 0-3.0%
The optical glass according to (1) or (2).

(4) The optical glass according to any one of (1) to (3), wherein the sum of the contents _{of the Ln 2} O ₃ components is 15.0% or more and 60.0% or less in terms of mass% of the oxide equivalent composition. In the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb)

(5) The optical glass according to any one of claims (1) to (4), wherein _{the mass sum (La 2} O ₃ + Y ₂ O ₃ ) of the oxide equivalent composition is 15.0% or more and 55.0% or less.

(6) The optical glass according to any one of (1) to (5), wherein _{the mass sum (Y 2} O ₃ + ZnO) of the oxide equivalent composition is 10.0% or more and 55.0% or less.

(7) Any of (1) to (6) in which _{the mass sum (La 2} O ₃ + Y ₂ O ₃ + ZnO + ZrO ₂ + Nb ₂ O ₅ + WO ₃ ) of the oxide conversion composition is 60.0% or more and 90.0% or less. The optical glass described.

(8) The description according to any one of (1) to (7), wherein _{the mass sum (La 2} O ₃ + Y ₂ O ₃ + ZnO + Nb ₂ O ₅ + WO ₃ ) of the oxide conversion composition is 60.0% or more and 85.0% or less. Optical glass.

(9) Any of (1) to (8) in which _{the mass ratio (La 2} O ₃ + Y ₂ O ₃ + Nb ₂ O ₅ + WO ₃ ) / (B ₂ O ₃ + ZnO) of the oxide conversion composition is 3.00 or less. The optical glass described.

(10) In the mass% of the oxide equivalent composition, _{the sum of the contents of the Rn 2} O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is 10.0% or less. Yes, any of (1) to (9) in which the sum of the contents of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 30.0% or less. The optical glass described.

(11) The optical glass according to any one of (1) to (10), wherein the glass transition point (Tg) is 620 ° C. or lower.

(12) Any of (1) to (11) in which the _{wavelength (λ 80} ) showing a spectral transmittance of 80% is 420 nm or less and the wavelength (λ _{5) showing a spectral transmittance of 5% is 355 nm or less.} The optical glass described.

(13) The optical glass according to any one of (1) to (12), which has a specific gravity of 5.00 or less.

(14) A preform material made of the optical glass according to any one of (1) to (13).

(15) An optical element made of the optical glass according to any one of (1) to (13).

(16) An optical device including the optical element according to (15).

According to the present invention, it is possible to obtain a glass having high devitrification resistance at a lower cost while _{having a refractive index (nd} ) and an Abbe number (ν _{d) within desired ranges.}

The optical glass of the present invention, in mass percent on the oxide composition in terms _of, B 2 _{O 3} component 40.0% 10.0% more than or less, _La 2 _{O 3} ingredient 15.0% or more 50.0% or less, It contains 10.0% or more and 45.0% or less of the ZnO component, and the mass sum (La ₂ O ₃ + Y ₂ O ₃ + ZnO) based on the oxide is 30.0 to 80.0%, which is 1.75 or more. It has a refractive index ( _nd ) of 1.88 or less, and has an Abbe number (ν _d ) of 35 or more and 45 or less. By the B ₂ O ₃ component and _La 2 _{O 3} component based, while having 1.75 or more 1.88 or less of the refractive index _{(n d)} and 35 to 45 following Abbe number ([nu _d) , It becomes easy to obtain stable glass. Further, the inventor of the present application has a high material cost by containing ZnO in a glass having _{a refractive index (nd ) of 1.75 or more and 1.88 or less and an Abbe number (ν d} ) of 35 or more and 45 or less. It has been found that glass can be stably produced even when the contents of the components, particularly the Ta ₂ O ₅ component and the Gd ₂ O _{3 component, are reduced.} Therefore, it is possible to obtain a highly stable optical glass at a lower cost while the refractive index ( _nd ) and the Abbe number (ν _{d) are within the desired ranges.}

In addition, since the optical glass of the present invention has a low specific gravity, it can be suitably used when the entire optical system is reduced in weight and size.

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 carried out with appropriate modifications within the scope of the object of the present invention. It should be noted that the description may be omitted as appropriate for the parts where the explanations are duplicated, but the gist of the 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, the content of each component shall be expressed in mass% with respect to the total mass of the oxide-equivalent composition, unless otherwise specified. Here, the "oxide-equivalent composition" is used when it is assumed that all the oxides, composite salts, metal fluorides and the like used as raw materials for the glass constituents of the present invention are decomposed into oxides at the time of melting. It is a composition in which each component contained in a glass is described, assuming that the total mass of the produced oxide is 100% by mass.

<About essential ingredients and optional ingredients>
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 10.0% or more, the devitrification resistance of the glass can be increased and the Abbe number of the glass can be increased. Therefore, the _{lower limit of the content of the B 2} O ₃ component is preferably 10.0%, more preferably 12.5%, still more preferably 15.0%, still more preferably 16.0%.
On the other hand, by _{setting the content of the B 2} O ₃ component to 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% or less, more preferably less than 35.0%, still more preferably less than 30.0%, still more preferably less than 25.0%.
B ₂ O ₃ component can be used _H 3 _BO 3 as a starting _{material, Na 2 B 4 O 7,} Na 2 B 4 O 7 · 10H 2 O, the BPO ₄ and the like.

The La ₂ O ₃ component is an essential component that increases the refractive index and Abbe number of glass. Therefore, _{the content of the La 2} O ₃ component is preferably 15.0% or more, more preferably more than 17.0%, still more preferably more than 20.0%, still more preferably more than 23.0%.
On the other hand, _{by reducing the content of the La 2} O ₃ component to 50.0% or less, devitrification can be reduced by increasing the stability of the glass, and an increase in the Abbe number more than necessary can be suppressed. In addition, the meltability of the glass raw material can be improved. Therefore, _{the content of the La 2} O ₃ component is preferably 50.0% or less, more preferably less than 45.0%, still more preferably less than 40.0%, still more preferably less than 35.0%.
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.

When the ZnO component is contained in an amount of 10% or more, it is an essential component that enhances the meltability of the raw material, promotes defoaming from the melted glass, and enhances the stability of the glass. It is also a component that can reduce the coloring of glass by shortening the melting time. It is also a component that can lower the glass transition point and improve the chemical durability. Therefore, the content of the ZnO component is preferably 10.0% or more, more preferably more than 12.0%, still more preferably more than 15.0%, still more preferably more than 18.0%.
On the other hand, by setting the content of the ZnO component to 45.0% or less, it is possible to suppress a decrease in the refractive index of the glass and reduce devitrification due to an excessive decrease in viscosity. Therefore, the content of the ZnO component is preferably 45.0% or less, more preferably less than 40.0%, still more preferably less than 35.0%, still more preferably less than 33.0%.
As the ZnO component, ZnO, ZnF _2, or the like can be used as a raw material.

The total amount (mass sum) of the La ₂ O ₃ component, the Y ₂ O _{3 component, and the Zn O component shall be 30.0% or more.} Thereby, the refractive index and Abbe number of the glass can be increased. Therefore, the sum of mass (La ₂ O ₃ + Y ₂ O ₃ + ZnO) is preferably 30.0% or more, more preferably 40.0% or more, still more preferably 45.0% or more, still more preferably 50.0%. As mentioned above, it is more preferably more than 56.0%.
On the other hand, by reducing the sum of masses to 80.0% or less, the stability of the glass can be enhanced and devitrification can be reduced. Therefore, the sum of mass (La ₂ O ₃ + Y ₂ O ₃ + ZnO) is preferably 80.0% or less, more preferably 75.0% or less, still more preferably 72.5% or less, still more preferably 70.0%. Hereinafter, it is more preferably less than 66.0%.

When the SiO ₂ component is contained in excess of 0%, the viscosity of the molten glass can be increased and the coloring of the glass can be reduced. It is also a component that enhances the stability of glass and makes it easier to obtain glass that can withstand mass production. Therefore, _{the content of the SiO 2} component may be preferably more than 0%, more preferably 1.0% or more, still more preferably 2.0% or more.
On the other hand, by _{setting the content of the SiO 2} component to 15.0% or less, an increase in the glass transition point can be suppressed and a decrease in the refractive index can be suppressed. Therefore, _{the content of the SiO 2} component is preferably 15.0% or less, more preferably less than 12.0%, still more preferably less than 10.0%, still more preferably less than 8.0%.
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.

ZrO ₂ component, when 0% ultra-containing, elevated refractive index of the glass and the Abbe number, which is an optional component that can and improving the devitrification resistance. Accordingly, the content of the ZrO ₂ component is preferably 0 percent, more preferably 0.5% or more, and more preferably be 1.0% or more.
On the other hand, by the content of the ZrO ₂ component below 15.0% can be reduced devitrification due to excessive content of the ZrO ₂ component. Therefore, the content of the ZrO ₂ component is preferably 15.0% or less, more preferably less than 12.0 percent, more preferably less than 10.0%, 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 Nb ₂ O ₅ component is an optional component whose devitrification resistance can be enhanced by increasing the refractive index of the glass and lowering the liquidus temperature of the glass when the content exceeds 0%. Therefore, _{the content of the Nb 2} O ₅ component may be preferably more than 0%, more preferably 2.0% or more, still more preferably 4.0% or more.
On the other hand, _{by reducing the content of the Nb 2} O ₅ component to 20.0% or less, the material cost of the glass can be suppressed. In addition, _{devitrification due to excessive inclusion of the Nb 2} O ₅ component can be reduced, and a decrease in the transmittance of the glass with respect to visible light (particularly, a wavelength of 500 nm or less) can be suppressed. Further, this can suppress a decrease in the Abbe number. Therefore, _{the content of the Nb 2} O ₅ component is preferably 20.0% or less, more preferably less than 15.0%, still more preferably less than 12.5%, still more preferably less than 10.0%.
As the Nb ₂ O _{5 component, Nb 2} O ₅ or the like can be used as a raw material.

When the WO ₃ component is contained in excess of 0%, it is an optional component that can increase the refractive index, lower the glass transition point, and enhance the devitrification resistance while reducing the coloring of the glass due to other high refractive index components. Is. Therefore, _{the content of the WO 3} component may be preferably more than 0%, more preferably 1.0% or more, still more preferably 2.0% or more.
On the other hand, _{by reducing the content of WO 3} component to 20.0% or less, the material cost of glass can be suppressed. Also, it increased visible light transmittance to reduce the coloration of the glass due WO ₃ components. Therefore, _{the content of the WO 3} component is preferably 20.0% or less, more preferably less than 15.0%, still more preferably less than 12.5%, still more preferably less than 10.0%.
As the WO _{3 component, WO 3} or the like can be used as a raw material.

Y ₂ O ₃ component, when ultra containing 0%, while maintaining a high refractive index and high Abbe number is suppressed the material cost of the glass, and can reduce the specific gravity of the glass than the other rare earth components It is an optional ingredient. _Accordingly, the content of Y 2 _{O 3} component is preferably 0 percent, more preferably 0.5% or more, and more preferably be 1.0% or more.
On the other hand, by _{setting the content of the Y 2} O ₃ component to 20.0% or less, the decrease in the refractive index of the glass can be suppressed and the stability of the glass can be improved. In addition, deterioration of the meltability of the glass raw material can be suppressed. _Accordingly, the content of Y 2 _{O 3} component is preferably 20.0% or less, more preferably less than 17.5%, more preferably less than 15.0%, more preferably less than 10.0%.
As the Y ₂ O _{3 component, Y 2} O ₃ , YF _3, or the like can be used as a raw material.

The Gd ₂ O ₃ component and the Yb ₂ O ₃ component are optional components that can increase the refractive index of the glass when the content exceeds 0%.
However, _{since the raw material prices of the Gd 2} O ₃ component and the Yb ₂ O ₃ component are high and the production cost is high when the content is high, the _{effect of reducing the Nb 2} O ₅ component, the WO ₃ component, etc. is diminished. Will be done. Further, _{by reducing the content of the Gd 2} O ₃ component and the Yb ₂ O ₃ component, an excessive increase in the Abbe number of the glass can be suppressed. Therefore, _{the contents of the Gd 2} O ₃ component and the Yb ₂ O ₃ component are preferably 20.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably 1. It is less than 0%, more preferably less than 0.5%, still more preferably less than 0.1%. In particular, from the viewpoint of reducing the material cost, it is most preferable not to contain these components.
As the Gd ₂ O ₃ component and the Yb ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ , Yb ₂ O _{3 and the} like can be used as raw materials.

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 they are contained in excess of 0%. In particular, the BaO component is a component that can increase the refractive index and also enhance the meltability of the glass raw material.
By setting the contents of the MgO component, the CaO component and the SrO component to 15.0% or less, the decrease in the refractive index can be suppressed and the devitrification due to the excessive content of these components can be reduced. .. Therefore, the contents of the MgO component, the CaO component and the SrO component are preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%, respectively. , More preferably less than 1.0%.
Further, by setting the content of the BaO component to 20.0% or less, a desired refractive index can be easily obtained, and devitrification due to excessive inclusion of these components can be reduced. Therefore, the content of the BaO component is preferably 20.0% or less, more preferably less than 15.0%, still more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably 1.0. It shall be less than%.
The MgO component, CaO component, SrO component and BaO component are raw materials such as MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF _{2 and the} like. Can be used.

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 the content exceeds 0%. Therefore, the _{contents of the Li 2} O component, the Na ₂ O component and the K ₂ O component may be preferably more than 0%, more preferably 0.5% or more, still more preferably 1.0% or more.
Of these, _{by reducing the Li 2} O component to 10.0% or less, it is difficult to reduce the refractive index of the glass, the devitrification of the glass can be reduced, and the viscosity of the glass is increased. Can be reduced. Therefore, _{the content of the Li 2} O component is preferably 10.0% or less, more preferably less than 7.5%, still more preferably less than 5.0%, still more preferably less than 2.5%, respectively.
Further, by _{setting the contents of the Na 2} O component and the K ₂ O component to 5.0% or less, the refractive index of the glass cannot be easily lowered and the devitrification of the glass can be reduced. Therefore, _{the contents of the Na 2} O component and the K ₂ O component are preferably 5.0% or less, more preferably less than 3.0%, still more preferably less than 1.0%, still more preferably 0.5%, respectively. Less than, more preferably less than 0.1%.
Li ₂ O component, Na ₂ O component and K ₂ O component are raw materials of Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO ₃ , Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF _{6, and the} like can be used.

The TiO ₂ component is an optional component whose stability can be enhanced by increasing the refractive index of the glass and lowering the liquidus temperature of the glass when the content exceeds 0%.
On the other hand, by the content of the TiO ₂ component to 10.0% or less, it is possible to reduce the devitrification due to excessive content of the TiO ₂ component, the decrease in transmittance of the glass in the visible light (in particular a wavelength of 500nm or less) It can be suppressed. Further, this can suppress a decrease in the Abbe number. Therefore, _{the content of the TiO 2} component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%, still more preferably 0. It is less than 5%, more preferably less than 0.1%.
As the TiO _{2 component, TiO 2} 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 enhance the devitrification resistance when it is contained in excess of 0%.
However, the Ta ₂ O ₅ component has a high raw material price, and the higher the content, the higher the production cost. Further, by _{setting the content of the Ta 2} O ₅ component to 10.0% or less, the melting temperature of the raw material is lowered, and the energy required for melting the raw material is reduced, so that the manufacturing cost of the optical glass can be reduced. Therefore, _{the content of the Ta 2} O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 1.0%, still more preferably less than 0.5%. It is preferably less than 0.1%. In particular, from the viewpoint of reducing the material cost, it is most preferable that _{the Ta 2} O _{5 component is not contained.}
As the Ta ₂ O _{5 component, Ta 2} O ₅ or the like can be used as a raw material.

The P ₂ O ₅ component is an optional component capable of lowering the liquidus temperature of the glass and increasing the devitrification resistance when the content exceeds 0%.
On the other hand, by _{setting the content of the P 2} O ₅ component to 10.0% or less, it is possible to suppress a decrease in the chemical durability of the glass, particularly the water resistance. Therefore, _{the content of the P 2} O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 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, and the} like can be used as raw materials.

The GeO ₂ component is an optional component capable of increasing the refractive index of the glass and improving the devitrification resistance when the content exceeds 0%.
However, _{since the raw material price of GeO 2} is high and the production cost is high when the content of _{GeO 2 is high, the effect of reducing the Gd 2} O ₃ component, the Ta ₂ O ₅ component, and the like is diminished. Therefore, _{the content of the GeO 2} component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%, still more preferably 0. It shall be less than 1%. From the viewpoint of reducing the material cost, it is not necessary to contain _{the GeO 2 component.}
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 the devitrification resistance of the molten glass when the content exceeds 0%.
On the other hand, by _{setting the content of each of the Al 2} O ₃ component and the Ga ₂ O ₃ component to 10.0% or less, the liquidus temperature of the glass can be lowered and the devitrification resistance can be improved. Therefore, _{the content of each of the Al 2} O ₃ component and the Ga ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, and further preferably less than 3.0%.
As the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) _{3 and the} like can be used as raw materials.

The Bi ₂ O ₃ 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, by _{setting the content of the Bi 2} O ₃ component to 10.0% or less, the liquidus temperature of the glass can be lowered and the devitrification resistance can be improved. Therefore, _{the content of the Bi 2} O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.
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 the content exceeds 0%.
On the other hand, TeO ₂ has a problem that it can be alloyed with platinum when the glass raw material is melted in a platinum crucible or a melting tank in which the portion in contact with the molten glass is made of platinum. Therefore, _{the content of the TeO 2} component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1. It shall be less than 0%.
As the TeO _{2 component, TeO 2} or the like can be used as a raw material.

The SnO ₂ component is an optional component that can reduce the oxidation of the molten glass to make it clear and increase the visible light transmittance of the glass when it is contained in an amount of more than 0%.
On the other hand, _{by reducing the content of the SnO 2} component to 3.0% or less, it is possible to reduce the coloring of the glass and the devitrification of the glass due to the reduction of the molten glass. Further, since _{the alloying of the SnO 2} component and the melting equipment (particularly 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 less than 1.0%, still more preferably less than 0.5%, still more preferably less than 0.1%.
As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF _4, or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component capable of defoaming the molten glass when it contains more than 0%.
On the other hand, _{if the amount of Sb 2} O ₃ is too large, the transmittance in the short wavelength region of the visible light region becomes poor. Therefore, _{the content of the Sb 2} O ₃ component is preferably 3.0% or less, more preferably less than 1.0%, still more preferably less than 0.5%, still more preferably less than 0.3%, most preferably less than 0.3%. 0.1% or less.
Sb ₂ O ₃ component can be used _{Sb 2 O 3, Sb 2 O} 5, Na 2 H 2 Sb 2 O 7 · 5H 2 O and the like as raw materials.

The component that clarifies and defoams the _{glass is not limited to the above Sb 2} O ₃ component, and a clarifying agent, a defoaming agent, or a combination thereof known in the field of glass production can be used.

The F component is an optional component capable of increasing the Abbe number of the glass, lowering the glass transition point, and improving the devitrification resistance when the content exceeds 0%.
However, when the content of the F component, that is, the total amount of fluoride substituted with a part or all of one or more oxides of each of the above-mentioned metal elements exceeds 15.0%, F Since the amount of volatilization of the components increases, it becomes difficult to obtain a stable optical constant, and it becomes difficult to obtain a homogeneous glass. In addition, the Abbe number rises more than necessary.
Therefore, the content of the F component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, still more preferably less than 3.0%.
The F component can be contained in glass by using, for example, ZrF ₄ , AlF ₃ , NaF, CaF _{2, etc. as a raw material.}

The sum (mass sum) of the contents of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 15.0% or more and 60.0% or less. Is preferable.
In particular, when the sum is 15.0% or more, the refractive index and Abbe number of the glass are increased, so that it is possible to easily obtain a glass having a desired refractive index and Abbe number. Therefore, _{the mass sum of the Ln 2} O ₃ components is preferably 15.0% or more, more preferably more than 20.0%, still more preferably more than 25.0%, still more preferably more than 30.0%.
On the other hand, when the sum is 40.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification of the glass can be reduced. In addition, it is possible to suppress an increase in the Abbe number more than necessary. Therefore, _{the mass sum of the Ln 2} O ₃ components is preferably 60.0% or less, more preferably less than 55.0%, still more preferably less than 45.0%, still more preferably less than 37.5%.

The total amount (sum of mass) of the La ₂ O ₃ component and the Y ₂ O ₃ component is preferably 15.0% or more and 55.0% or less. In particular, by setting this sum to 15.0% or more, the refractive index and Abbe number of the glass can be increased. Therefore, the mass sum (La ₂ O ₃ + Y ₂ O ₃ ) is preferably 15.0% or more, more preferably 17.0% or more, still more preferably 20.0% or more, still more preferably 25.0% or more. , More preferably more than 30.0%.
On the other hand, by reducing the sum of masses to 55.0% or less, the stability of the glass can be improved and devitrification can be reduced. Therefore, the sum of mass (La ₂ O ₃ + Y ₂ O ₃ ) is preferably 55.0% or less, more preferably 50.0% or less, still more preferably 47.5% or less, still more preferably 45.0% or less. , More preferably less than 41.0%.

The total amount (sum of mass) of the Y ₂ O ₃ component and the Zn O component is preferably 10.0% or more and 55.0% or less. In particular, by setting this sum to 10.0% or more, the refractive index and Abbe number of the glass can be increased, and the chemical durability can be improved. Therefore, the mass sum (Y ₂ O ₃ + ZnO) is preferably 10.0% or more, more preferably 12.0% or more, still more preferably 15.0% or more, still more preferably 18.0% or more, still more preferably. Is 20.0% or more.
On the other hand, by setting the sum of mass to 55.0% or less, a decrease in the refractive index of the glass can be suppressed. Therefore, the sum of mass (Y ₂ O ₃ + ZnO) is preferably 55.0% or less, more preferably 50.0% or less, still more preferably 45.0% or less, still more preferably 40.0% or less, still more preferably. Is 38.0% or less.

The total amount (mass sum) of La ₂ O ₃ component, Y ₂ O ₃ component, ZnO component, ZrO ₂ component, Nb ₂ O ₅ component, and WO ₃ component is preferably 60.0% or more and 90.0% or less. .. In particular, by setting this sum to 60.0% or more, the refractive index and Abbe number of the glass can be increased, and the chemical durability can be improved. Therefore, the sum of masses (La ₂ O ₃ + Y ₂ O ₃ + ZnO + ZrO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 60.0% or more, more preferably 65.0% or more, still more preferably 70.0% or more. It is more preferably 72.0% or more, still more preferably more than 73.0%.
On the other hand, by setting the sum of mass to 90.0% or less, the devitrification resistance of the glass can be improved. Therefore, the sum of masses (La ₂ O ₃ + Y ₂ O ₃ + ZnO + ZrO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 90.0% or less, more preferably 85.0% or less, still more preferably 82.0% or less. It is more preferably 80.0% or less, still more preferably 78.0% or less.

The total amount (mass sum) of the La ₂ O ₃ component, the Y ₂ O ₃ component, the Zn _{O component, the Nb 2} O ₅ component, and the WO ₃ component is preferably 60.0% or more and 85.0% or less. In particular, by setting this sum to 60.0% or more, the refractive index and Abbe number of the glass can be increased, and the chemical durability can be improved. Therefore, the sum of masses (La ₂ O ₃ + Y ₂ O ₃ + ZnO + Nb ₂ O ₅ + WO ₃ ) is preferably 60.0% or more, more preferably 62.5% or more, still more preferably 65.0% or more, still more preferably. Is over 69.7%.
On the other hand, by setting the sum of mass to 85.0% or less, the devitrification resistance of the glass can be improved. Therefore, the sum of masses (La ₂ O ₃ + Y ₂ O ₃ + ZnO + Nb ₂ O ₅ + WO ₃ ) is preferably 85.0% or less, more preferably 82.5% or less, still more preferably 80.0% or less, still more preferably. Is 77.5% or less.

The ratio (mass ratio) of the total amount of the La ₂ O ₃ component, the Y ₂ O ₃ component, the Nb ₂ O ₅ component, and the WO ₃ component to the total amount of the B ₂ O _{3 and Zn O components is preferably 3.00 or less.} .. In particular, by setting this mass ratio to more than 0%, the stability of the glass can be improved. Therefore, this mass ratio may be preferably more than 0%, more preferably 0.1% or more, still more preferably 0.3% or more, still more preferably 0.5% or more. On the other hand, by setting this mass ratio to 3.00 or less, the devitrification resistance of the glass can be enhanced and the deterioration of the chemical durability can be suppressed. Therefore, the mass ratio (La ₂ O ₃ + Y ₂ O ₃ + Nb ₂ O ₅ + WO ₃ ) / (B ₂ O ₃ + ZnO) is preferably 3.00 or less, more preferably 2.50 or less, still more preferably 1. It is 5 or less, more preferably 1.30 or less.

The sum (mass sum) of the contents of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 10.0% or less. In particular, by setting this mass sum to more than 0%, the meltability of the glass can be improved and the glass transition point can be lowered. Therefore, this mass ratio may be preferably more than 0%, more preferably 0.1% or more, still more preferably 0.3% or more, still more preferably 0.5% or more. On the other hand, by setting the sum of mass to 10.0% or less, it is possible to suppress a decrease in the viscosity of the molten glass, make it difficult to decrease the refractive index of the glass, and reduce the devitrification of the glass. Therefore, _{the mass sum of the Rn 2} O components is preferably 10.0% or less, more preferably less than 7.5%, still more preferably less than 5.0%, still more preferably less than 2.5%.

The sum (mass sum) of the contents of the RO component (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 30.0% or less. As a result, a decrease in the refractive index can be suppressed, and the stability of the glass can be improved. Therefore, the mass sum of the RO components is preferably 30.0% or less, more preferably less than 20.0%, still more preferably less than 10.0%, still more preferably less than 5.0%.

<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 preferable to be contained will be described.

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

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

Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to refrain from being used as a harmful chemical substance in recent years, and is used not only in the glass manufacturing process but also in the processing process and disposal after commercialization. Up to this point, environmental measures are required. Therefore, when the environmental impact is emphasized, it is preferable that these are not substantially contained.

[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 the temperature is 1500 to 1500 ° C. in an electric furnace according to the difficulty of melting the glass raw material. It is produced by melting in the temperature range of 2 to 5 hours, stirring and homogenizing, lowering the temperature to an appropriate temperature, casting into a mold, and slowly cooling.

At this time, it is preferable to use a glass raw material having high meltability. As a result, melting at a lower temperature and melting in a shorter time become possible, so that the productivity of glass can be increased and the production cost can be reduced. In addition, since the volatilization of the components and the reaction with the crucible are reduced, it is possible to easily obtain a glass with less coloring.

[Physical characteristics]
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 ( _nd ) of the optical glass of the present invention is preferably 1.75, more preferably 1.77, and even more preferably 1.79 as the lower limit. The refractive index ( _nd ) may be preferably 1.88, more preferably 1.86, and even more preferably 1.84 as the upper limit.
_{The Abbe number (ν d} ) of the optical glass of the present invention is preferably 35, more preferably 36, and even more preferably 38 as the lower limit. The Abbe number (ν _d ) is preferably up to 45, more preferably 44, and even more preferably 42.5.
By having such a high refractive index, a large amount of refraction of light can be obtained even if the optical element is made thinner. Further, by having such a low dispersion, it is possible to reduce the focus shift (chromatic aberration) due to the wavelength of light when used as a single lens. Therefore, for example, when an optical system is configured by combining with an optical element having a high dispersion (low Abbe number), it is possible to reduce aberrations as a whole of the optical system and achieve high imaging characteristics and the like.
As described above, the optical glass of the present invention is useful in optical design, and particularly when the optical system is configured, the optical system can be miniaturized while achieving high imaging characteristics and the like, and the optical design can be achieved. The degree of freedom can be expanded.

The optical glass of the present invention preferably has a glass transition point (Tg) of 620 ° C. or lower. Since the optical glass has a glass transition point of 620 ° C. or lower, the glass softens at a lower temperature, so that the glass can be easily press-molded at a lower temperature even when the optical glass is used for press molding. .. Therefore, the glass transition point of the optical glass of the present invention is preferably 620 ° C. or lower, more preferably 600 ° C. or lower, and further preferably 580 ° C. or lower.

It is preferable that the optical glass of the present invention has a high visible light transmittance, particularly a light transmittance on the short wavelength side of visible light, and thus less coloring.
In particular, in the optical glass of the present invention, the wavelength (λ ₈₀ ) showing a spectral transmittance of 80% in a sample having a thickness of 10 mm is preferably 420 nm, more preferably 415 nm, and further preferably 410 nm in terms of glass transmittance. The upper limit.
Further, 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 355 nm, more preferably 350 nm, and further preferably 345 nm as the upper limit.
As a result, the absorbing edge of the glass becomes an ultraviolet region or its vicinity, 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 such as a lens that transmits light.

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 or less. As a result, the mass of the optical element and the optical device using the optical element is reduced, which can contribute to the weight reduction of the optical device. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.00, more preferably 4.80, and preferably 4.70 as the upper limit. The specific gravity of the optical glass of the present invention is often 3.00 or more, more specifically 3.30 or more, and more specifically 3.50 or more.

[Preform material and optical element]
From the produced optical glass, a glass molded body can be produced by using, for example, polishing means or mold press molding means such as reheat press molding or precision press molding. That is, a glass molded body is produced by performing machining such as grinding and polishing on optical glass, or a preform for mold press molding is produced from optical glass, and reheat press molding is performed on this preform. After that, a glass molded body is produced by polishing, a preform produced by polishing, or a preform formed by a known levitation molding or the like is subjected to precision press molding to produce a glass molded body. Can be produced. The means for producing the glass molded body is not limited to these means.

As described above, the optical glass of the present invention is useful for various optical elements and optical designs. Among them, 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. This makes it possible to form a preform with a large diameter, so that while increasing the size of the optical element, it has high-definition and high-precision imaging characteristics and projection characteristics when used in optical equipment such as cameras and projectors. Can be realized.

The composition of the examples of the present invention, _{and the wavelengths (λ 5) showing the refractive index (nd} ), Abbe number (ν _d ), glass transition point (Tg), and spectral transmittance of these glasses of 5% and 80%. , Λ ₈₀ ), and the results of specific gravity are shown in Tables 1 to 7. The following examples are for purposes of illustration only, and are not limited to these examples.

The glasses of Examples and Comparative Examples of the present invention are ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphoric acid compounds, which correspond to each other as raw materials for each component. The high-purity raw materials used in the above 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, depending on the difficulty of melting the glass raw material. The mixture was melted in an electric furnace in a temperature range of 1100 to 1500 ° C. for 2 to 5 hours, homogenized by stirring, cast into a mold or the like, and slowly cooled.

Here, the refractive index of the glass of Example and Comparative Example _{(n d)} is indicated by the measured value for the helium lamp d line (587.56 nm). The Abbe number (ν _d ) is the refractive index of the d line, the refractive index of the hydrogen lamp with respect to the F line (486.13 nm) (n _F ), and the refractive index of the hydrogen lamp with respect to the C line (656.27 nm) (n _C ). It was calculated from the formula of Abbe number (ν _d ) = [(n _d -1) / (n _F −n _{C)] using the value of.} The glass used for this measurement was treated in a slow cooling furnace at a slow cooling rate of −25 ° C./hr.

The glass transition point (Tg) of the glass of Examples and Comparative Examples is determined by measuring the relationship between the temperature and the elongation of the sample in accordance with the Japan Optical Glass Industry Association standard JOBIS08-2003 “Method for measuring thermal expansion of optical glass”. It was obtained from the obtained thermal expansion curve.

The transmittance of the glass of Examples and Comparative Examples was measured according to the Japan Optical Glass Industry Association standard JOBIS02-2003. In the present invention, the presence or 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 according to JISZ8722, and λ ₅ (wavelength at a transmittance of 5%) and λ ₈₀ (transmittance). The wavelength at 80%) was determined.

The specific gravities of the glasses of Examples and Comparative Examples were measured based on the Japan Optical Glass Industry Association standard JOBIS05-2015 "Method of measuring the specific densities of optical glass".

As shown in these tables, the optical glass of the embodiment of the present invention _{does not contain expensive components, particularly Ta 2} O ₅ component and Gd ₂ O ₃ component, and can be obtained at a lower cost.

Further, the optical glass of the embodiment of the present invention has a mass sum of La ₂ O ₃ + Y ₂ O ₃ + ZnO of 30.0% or more and 80.0% or less, and is stable while increasing the refractive index and Abbe number of the glass. High glass can be produced.

The optical glasses of Examples of the present invention are both refractive index _{(n d)} of 1.75 or more, with more particularly 1.79 or more, the refractive index _{(n d)} is 1.88 or less More specifically, it was 1.84 or less, which was within the desired range.

Further, in each of the optical glasses of the examples of the present invention, the Abbe number (ν _d ) is 45 or less, more specifically 42.5 or less, and the Abbe number (ν _d ) is 35 or more, more specifically. Was 42.5 or more, which was within the desired range.

Therefore, it was clarified that the optical glass of the example of the present invention is a glass _{having high stability while having a refractive index (nd} ) and an Abbe number (ν _d ) within desired ranges.

In addition, the optical glass of the examples of the present invention had a glass transition point (Tg) of 620 ° C. or lower, more specifically 580 ° C. or lower.
Further, in the optical glass of the example of the present invention, λ ₈₀ (wavelength at the time of transmittance 80%) was 420 nm or less, and more specifically, 410 nm or less.
Further, in the optical glass of the example of the present invention, λ ₅ (wavelength at a transmittance of 5%) was 355 nm or less, and more specifically, 345 nm or less.
Further, all of the optical glasses of the examples of the present invention had a specific gravity of 5.00 or less, more specifically 4.70 or less.

From this, it can be inferred that the optical glass of the embodiment of the present invention has a low glass transition point, a high transmittance for visible light, and a small specific gravity.

On the other hand, the optical glass of the comparative example, ZnO component less and 7.21%, _{(n d)} and Abbe number ([nu _d) not within the desired range, lambda ₈₀ (wavelength when the transmittance 80%) Is as high as 508 nm.

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

Claims (6)

By mass% of oxide equivalent composition,
B ₂ O ₃ component 10.0 to less than 30.0%,
La ₂ O ₃ component 15.0-40.0%,
SiO ₂ component 0-less than 8.0%,
ZrO ₂ component 0-less than 5.0%,
Less than ZnO component 20.29~35.0% _Nb 2 _O less than ₅ components from 5.3 to 15.0%,
WO ₃ component 4.2 to less than 10.0%,
Gd ₂ O ₃ component 0-less than 1.0%,
Li ₂ O component 0.5-less than 5.0%,
TiO ₂ component 0-less than 1.0%,
Ta ₂ O ₅ component 0-less than 1.0%,
And
The sum of mass (La ₂ O ₃ + Y ₂ O ₃ + ZnO) based on the oxide is 40.0 to 80.0%,
The mass sum (La ₂ O ₃ + Y ₂ O ₃ + ZnO + ZrO ₂ + Nb ₂ O ₅ + WO ₃ ) based on the oxide is 70.0 to 78.0%.
The refractive index (nd) is 1.75 to 1.84, and the Abbe number (νd) is 35 to 45.
Glass transition point (Tg) is 567 ° C or less,
Transmittance (λ ₈₀ ) is 410 nm or less,
Optical glass characterized by being. By mass% of oxide equivalent composition,
Y ₂ O ₃ component 0 to 20.0%,
Yb ₂ O ₃ component 0 to 20.0%,
MgO component 0 to 15.0%,
CaO component 0 to 15.0%,
SrO component 0 to 15.0%,
BaO component 0-20.0%,
Na ₂ O component 0-5.0%,
K ₂ O component from 0 to 5.0%,
Bi ₂ O ₃ component 0 to 10.0%,
P ₂ O ₅ component 0 to 10.0%,
Al ₂ O ₃ component 0 to 10.0%,
Ga ₂ O ₃ component 0 to 10.0%,
GeO ₂ component 0-10.0%,
TeO ₂ component 0 to 15.0%,
SnO ₂ component 0-3.0% and Sb ₂ O ₃ component 0-3.0%
The optical glass according to claim 1. The optical glass according to any one of claims 1 to 2, wherein the mass ratio (La ₂ O ₃ + Y ₂ O ₃ + Nb ₂ O ₅ + WO ₃ ) / (B ₂ O _{3 + ZnO) of the oxide conversion composition is 3.00 or less.} .. A preform material made of optical glass according to any one of claims 1 to 3. An optical element made of the optical glass according to any one of claims 1 to 3. An optical device including the optical element according to claim 5.