JP2017105703A - Optical glass, preform and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain optical glass that has high devitrification resistance while having a refractive index (n) and an Abbe number (ν) in desired ranges, at reduced costs.SOLUTION: An optical glass has, in mass%, SiOcomponents of 15.0-50.0%, NbOcomponents of 25.0-50.0%, and BOcomponents of 1.0-20.0%. The optical glass has high transparency with respect to visible light, and prevents opacification, devitrification or fogging from occurring during glass making and processing in a reheat press step.SELECTED DRAWING: Figure 2

Description

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

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

Among optical glasses for producing optical elements, in particular, it has a refractive index (n _d ) of 1.65 or more and an Abbe number of 28 or more and 45 or less (which can reduce the weight and size of the entire optical system). There is a great demand for optical glasses having ν _d ). As such an optical glass, an optical glass mainly composed of a SiO ₂ —Nb ₂ O ₅ system represented by Patent Documents 1 and ₂ is known.

JP 2007-169157 A Special republication WO02 / 014235

  As a method for producing an optical element from optical glass, for example, a gob or glass block formed from optical glass is ground and polished to obtain the shape of the optical element, or a gob or glass formed from optical glass. A method of grinding and polishing a glass molded product obtained by reheating and molding a block (reheat press molding), and molding a preform material obtained from a gob or glass block with an ultra-precision machined mold A method of obtaining the shape of an optical element by (precise mold press molding) is known. Any method is required to obtain a stable glass when a gob or glass block is formed from a molten glass raw material. Here, when the stability (devitrification resistance) with respect to devitrification of the glass which comprises the gob or glass block obtained falls and a crystal | crystallization generate | occur | produces inside glass, it can no longer obtain glass suitable as an optical element. Can not.

In an optical glass mainly composed of a SiO ₂ —Nb ₂ O ₅ system having a refractive index (n _d ) of 1.65 or more and an Abbe number (νd) of 28 to 45, the optical glass after reheat press molding The stability of the glass is poor, and a strong milky white tendency and a significant devitrification tendency occur inside the glass. Therefore, in the manufacturing method in which the shape is created through a reheating process such as reheat press molding, the optical glass has poor stability and an optical glass with good quality cannot be obtained.

In addition, in order to reduce the material cost of the optical glass, it is desirable that the raw material costs of the components constituting the optical glass be as low as possible. Moreover, when mass-producing optical glass, it is desired that devitrification at the time of glass production hardly occurs. However, it is difficult to say that the glass compositions described in Patent Documents 1 and 2 sufficiently satisfy these various requirements.

The present invention has been made in view of the above-described problems, and the object of the present invention is to provide milk white / white in the glass while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. The object is to obtain an optical glass that does not devitrify at a lower cost.

As a result of intensive studies to solve the above problems, the inventors of the present invention contain a SiO ₂ component and a Nb ₂ O ₅ component, and contain a B ₂ O ₃ component in an amount of 1.0 to 20.0%. In optical glass, it discovered that the glass milk white and devitrification in the reheat press process could be obtained, and came to complete this invention.

(1) In mass% of oxide equivalent composition,
15.0-50.0% of SiO ₂ component,
25.0-50.0% of Nb ₂ O ₅ component,
Containing B ₂ O ₃ component 1.0-20.0%,
Optical glass in which devitrification and milky white do not occur before and after the reheating test (A).
[Reheating test (A): Reheating test pieces 15 mm × 15 mm × 30 mm, raising the temperature from room temperature to a temperature 100 ° C. to 120 ° C. higher than the transition temperature (Tg) of each sample in 150 minutes. The sample is kept at a temperature 100 ° C. to 120 ° C. higher than the glass transition temperature (Tg) for 30 minutes, then naturally cooled to room temperature, and the two opposing surfaces of the test piece are polished to a thickness of 10 mm and visually observed. ]

(2) In mass% of oxide equivalent composition,
ZnO component 0 to 25.0%,
ZrO ₂ component 0 to 20.0%,
The optical glass of (1).

(3) In mass% of oxide equivalent composition,
TiO ₂ component 0 to 15.0%,
WO ₃ component 0-10.0%,
MgO component 0 to 10.0%,
CaO component 0 to 10.0%,
SrO component 0 to 10.0%,
BaO component 0 to 10.0%,
La ₂ O ₃ component 0 to 10.0%,
Gd ₂ O ₃ component 0 to 10.0%,
Y ₂ O ₃ component 0 to 10.0%,
Yb ₂ O ₃ component 0 to 10.0%,
Li ₂ O component 0 to 20.0%,
Na ₂ O component 0 to 20.0%,
K ₂ O component 0 to 10.0%,
Ta ₂ O ₅ component 0 to 10.0%,
P ₂ O ₅ component 0 to 10.0%,
GeO ₂ component 0 to 10.0%,
Al ₂ O ₃ component 0 to 10.0%,
Ga ₂ O ₃ component 0 to 10.0%,
Bi ₂ O ₃ component 0 to 10.0%,
TeO ₂ components 0 to 5.0%, and SnO ₂ containing components 0 to 1.0% _Sb 2 _{O 3} component from 0 to 1.0%
The optical glass according to any one of (1) and (2).

(4) The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) in the mass percentage based on the oxide is 0 to 15.0%. , Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K) is 0 to 30.0% by mass, RO component (wherein R is Mg, Ca, The optical glass according to any one of (1) to (3), wherein a mass sum of one or more selected from the group consisting of Sr and Ba is 0 to 20.0%.

  (5) The optical glass according to any one of (1) to (4), wherein the refractive index (nd) is 1.65 to 1.80 and the Abbe number (νd) is 28 to 45.

(6) The wavelength (λ ₈₀ ) at which the spectral transmittance is 80% is 450 nm or less, and the wavelength (λ ₅ ) at which the spectral transmittance is 5% is 365 nm or less, any one of (1) to (5) The optical glass described.

  (7) An optical element made of the optical glass according to any one of (1) to (6).

  (8) A preform for polishing and / or precision press molding comprising the optical glass according to any one of (1) to (6).

  (9) An optical apparatus comprising the optical element according to any one of (7) and (8).

According to the present invention, an optical glass with reduced glass milk white and devitrification in a reheat press process can be obtained at a lower cost while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. it can.

It is a figure which shows the normal line by which partial dispersion ratio ((theta) g, F) is represented on the orthogonal coordinate of a vertical axis | shaft and Abbe number ((nu) _d ) on a horizontal axis. It is a figure which shows the relationship between the partial dispersion ratio ((theta) g, F) and the Abbe number ((nu) _d ) about the Example of this application.

The optical glass of the present invention is the mass% of the oxide conversion composition, the SiO ₂ component is 15.0 to 50.0%, the Nb ₂ O ₅ component is 20.0 to 50.0%, and the B ₂ O ₃ component is It contains 1.0 to 20.0%, and devitrification and milky white do not occur before and after the reheating test (I).
In glass containing SiO ₂ component and Nb ₂ O ₅ component, devitrification and milky whiteness are reduced when glass is reheated while having high refractive index and low Abbe number (high dispersion) within the desired range. Therefore, an optical glass suitable for reheat press molding can be obtained.

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

[Glass component]
The composition range of each component constituting the optical glass of the present invention is described below. 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%.

<About essential and optional components>
The SiO ₂ component is an essential component that promotes stable glass formation and reduces devitrification (generation of crystalline substances), which is not desirable as an optical glass.
In particular, when the content of the SiO ₂ component is 15.0% or more, a glass having excellent devitrification resistance can be obtained without significantly increasing the partial dispersion ratio. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Therefore, the content of the SiO ₂ component is preferably 15.0%, more preferably 18.0%, further preferably 20.0%, further preferably 25.0%, and further preferably 27.0%. And
On the other hand, when the content of the SiO ₂ component is 50.0% or less, the refractive index is hardly lowered, so that a desired high refractive index can be easily obtained, and an increase in the partial dispersion ratio can be suppressed. Moreover, the fall of the meltability of a glass raw material can be suppressed by this. Therefore, the content of the SiO ₂ component is preferably 50.0%, more preferably 48.0%, further preferably 45.0%, and further preferably 40.0%.
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 Nb ₂ O ₅ component is an essential component that can increase the refractive index, reduce the Abbe number and the partial dispersion ratio, and increase the resistance to devitrification.
In particular, by setting the content of the Nb ₂ O ₅ component to 25.0% or more, the refractive index is increased to the target optical constant, and the anomalous dispersion is reduced by adjusting the component within the range of the present invention. can do. Therefore, the content of the Nb ₂ O ₅ component is preferably 25.0%, more preferably 28.0%, and still more preferably 30.0%.
On the other hand, by the content of _Nb 2 _{O 5} component below 50.0%, thereby reducing the material cost of the glass. Further, to suppress an increase in melting temperature at the time of glass production, it and reduce the devitrification due to excessive content of Nb ₂ O ₅ component. Therefore, the content of the Nb ₂ O ₅ component is preferably 50.0%, more preferably 45.0%, and still more preferably 43.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

When the B ₂ O ₃ component is contained in an amount of more than 0%, it is an optional component that can enhance the devitrification resistance and promote the meltability of the glass raw material by promoting stable glass formation. Therefore, the content of the B ₂ O ₃ component is preferably 1.0%, more preferably 3.0%, and still more preferably 4.0%.
On the other hand, when the content of the B ₂ O ₃ component is 20.0% or less, a decrease in the refractive index can be suppressed and an increase in the partial dispersion ratio can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 20.0%, more preferably 15.0%, still more preferably 12.0%, and still more preferably 10.0%.
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 ratio of the sum of the SiO ₂ component and the B ₂ O ₃ component to the content of the Nb ₂ O ₅ component is preferably less than 2.0. As a result, the target optical constant can be adjusted while maintaining anomalous dispersion. Therefore, (SiO ₂ + B ₂ O ₃ ) / Nb ₂ O ₅ is preferably less than 2.0, more preferably less than 1.7, still more preferably less than 1.5, and still more preferably less than 1.4.
On the other hand, when (SiO ₂ + B ₂ O ₃ ) / Nb ₂ O ₅ exceeds 0, the glass can be stabilized and devitrified. Therefore, (SiO ₂ + B ₂ O ₃ ) / Nb ₂ O ₅ is preferably more than 0, more preferably 0.5 or more, still more preferably 0.8 or more, and further preferably 0.9 or more.

The ZnO component is an optional component that is inexpensive and can lower the glass transition point when it contains more than 0%. Therefore, the content of the ZnO component is preferably more than 0%, more preferably more than 0.5%, and even more preferably more than 1.0%.
On the other hand, when the content of the ZnO component is 25.0% or less, chemical durability can be enhanced while reducing devitrification and coloring during reheating of the glass. Therefore, the content of the ZnO component is preferably 25.0% or less, more preferably 20.0% or less, still more preferably less than 16.0%, and even more preferably less than 10.0%.

The ZrO ₂ component is an optional component that can increase the refractive index and Abbe number of the glass, lower the partial dispersion ratio, and increase the devitrification resistance when it contains more than 0%. Moreover, devitrification and coloring at the time of reheating can be reduced thereby. Therefore, the content of the ZrO 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 3.0%.
On the other hand, by setting the content of the ZrO ₂ component to 20.0% or less, devitrification can be reduced, and more uniform glass can be easily obtained. Therefore, the content of the ZrO ₂ component is preferably 20.0%, more preferably 18.0%, still more preferably 15.0%, and still more preferably 11.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The TiO ₂ component is an optional component that increases the refractive index, decreases the Abbe number, and increases the devitrification resistance when the content is more than 0%.
On the other hand, when the content of the TiO ₂ component is 15.0% or less, the coloring of the glass can be reduced and the internal transmittance can be increased. In addition, this makes it difficult to increase the partial dispersion ratio, so that a desired low partial dispersion ratio close to the normal line can be easily obtained. Accordingly, the content of the TiO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, and even more preferably less than 5.0%. In particular, from the viewpoint of reducing the anomalous dispersibility of glass, it is not more preferable.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The WO ₃ component is an optional component that can increase the refractive index and decrease the Abbe number, increase the devitrification resistance, and increase the meltability of the glass raw material when it contains more than 0%.
On the other hand, by making the content of the WO ₃ component 10.0% or less, it is possible to make it difficult to raise the partial dispersion ratio of the glass, and to reduce the coloring of the glass and to increase the internal transmittance. Therefore, the content of the WO ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and even more preferably less than 1.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

The MgO component is an optional component that can lower the melting temperature of the glass when it exceeds 0%.
On the other hand, by setting the content of the MgO component to 10.0% or less, devitrification can be reduced while suppressing a decrease in the refractive index. Therefore, the content of the MgO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably less than 1.0%.
As the MgO component, MgO, MgCO ₃ , MgF ₂ or the like can be used as a raw material.

When the CaO component is contained in an amount of more than 0%, it is an optional component that can reduce the Abbe number, reduce devitrification, and increase the meltability of the glass raw material while reducing the material cost of the glass. Therefore, the content of the CaO 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 making the content of the CaO component 10.0% or less, a decrease in refractive index, an increase in Abbe number, and an increase in partial dispersion ratio can be suppressed, and devitrification can be reduced. Therefore, the content of the CaO component is preferably 10.0%, more preferably 9.0%, still more preferably 8.0%, and still more preferably 6.0%.
As the CaO component, CaCO ₃ , CaF ₂ or the like can be used as a raw material.

The SrO component is an optional component that can increase the refractive index and increase the resistance to devitrification when it contains more than 0%.
In particular, deterioration of chemical durability can be suppressed by setting the content of the SrO component to 10.0% or less. Therefore, the content of the SrO component is preferably 10.0%, more preferably less than 8.0%, and still more preferably less than 4.0%.
As the SrO component, Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

When the BaO component is contained in excess of 0%, the refractive index can be increased, the partial dispersion ratio can be lowered, the devitrification resistance can be increased, the melting property of the glass raw material can be increased, and other alkaline earth components It is an optional component that can reduce the material cost of glass compared to
In particular, by making the content of the BaO component 10.0% or less, deterioration of chemical durability and devitrification can be suppressed. Accordingly, the content of the BaO component is preferably 10.0% or less, more preferably less than 8.0%, even more preferably less than 4.0%, and even more preferably less than 2.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ or the like can be used as a raw material.

La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are optional components that can increase the refractive index and reduce the partial dispersion ratio by containing at least one of them in excess of 0%. It is an ingredient.
In particular, by increasing the content of each of the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component to 10.0% or less, an increase in the Abbe number can be suppressed, and the specific gravity The devitrification can be reduced, and the material cost can be reduced. Accordingly, the content of each of the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component, and Yb ₂ O ₃ component is preferably 10.0% or less, more preferably 5.0% or less, Preferably it is 3.0% or less, More preferably, you may be less than 1.0%.
La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component are La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer), Y ₂ O ₃ , YF ₃ , Gd ₂ O ₃ , GdF ₃ , Yb ₂ O _{3 and the} like can be used.

The Li ₂ O component is an optional component that can lower the partial dispersion ratio, lower the glass transition point, and improve the meltability of the glass raw material when it contains more than 0%. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably more than 1.0%, still more preferably 2.0% or more, still more preferably more than 3.0%, most preferably 5.0. It may be more than%.
On the other hand, by setting the content of the Li ₂ O component to 20.0% or less, a decrease in refractive index can be suppressed, chemical durability can hardly be deteriorated, and devitrification due to excessive content can be reduced.
Therefore, the content of the Li ₂ O component is preferably 20.0% or less, more preferably 15.0% or less, and even more preferably less than 10.0%.
For the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF, or the like can be used as a raw material.

The Na ₂ O component is an optional component that can lower the partial dispersion ratio, lower the glass transition point, and improve the meltability of the glass raw material when it contains more than 0%. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably more than 0.3%, even more preferably more than 0.5%, and even more preferably more than 1.0%.
On the other hand, by setting the content of the Na ₂ O component to 20.0% or less, a decrease in refractive index can be suppressed, chemical durability can hardly be deteriorated, and devitrification due to excessive content can be reduced.
Therefore, the content of the Na ₂ O component is preferably 20.0% or less, more preferably 15.0% or less, and even more preferably less than 10.0%.
As the Na ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like can be used as a raw material.

K 2 _O component, when 0% ultra containing one at least, elevated meltability of the glass raw material, which is an optional component and can be lowered glass transition temperature.
On the other hand, by setting the content of the K ₂ O component to 10.0% or less, an increase in the partial dispersion ratio can be suppressed, devitrification can be reduced, and chemical durability can hardly be deteriorated. Therefore, the content of the K ₂ O component is preferably 10.0% or less, more preferably less than 8.0%, and even more preferably less than 5.0%.
As the K ₂ O component, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ 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, decrease the Abbe number and the partial dispersion ratio, and increase the devitrification resistance when the content exceeds 0%.
On the other hand, by making the content of Ta ₂ O ₅ component 10.0% or less, the amount of Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, and the glass is easily melted at a lower temperature. Glass production costs can be reduced. Moreover, this can reduce the devitrification of the glass due to excessive inclusion of the Ta ₂ O ₅ component. 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 3.0%, and even more preferably less than 1.0%. In particular, from the viewpoint of reducing the material cost of glass, the Ta ₂ O ₅ component may not be contained.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that enhances the stability of the glass.
On the other _hand, when the content of P 2 _{O 5} component to 10.0% or _less, can be reduced devitrification due to excessive content of P 2 _{O 5} component. 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%, and even more preferably less than 1.0%.
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 and reduce devitrification when it contains more than 0%.
On the other hand, by making the content of the GeO ₂ component 10.0% or less, the amount of expensive GeO ₂ component used is reduced, so that the material cost of the glass can be reduced. 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%, and even more preferably less than 1.0%.
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 chemical durability and improve devitrification resistance when at least one of them is contained in excess of 0%.
On the other hand, devitrification due to excessive inclusion of Al ₂ O ₃ component or Ga ₂ O ₃ component is reduced by making each content of Al ₂ O ₃ component and Ga ₂ O ₃ component 10.0% or less. it can. Accordingly, 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%, still more preferably less than 3.0%, and even more preferably 1. Less than 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 Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the Abbe number 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 10.0% or less, it is possible to make it difficult to increase the partial dispersion ratio, and it is possible to reduce the coloring of the glass and increase the internal transmittance. 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%, and even 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, lower the partial dispersion ratio, and lower the glass transition point when contained in excess of 0%.
On the other hand, by setting the content of the TeO ₂ component to 5.0% or less, the coloring of the glass can be reduced and the internal transmittance can be increased. Moreover, glass with lower material costs can be obtained by reducing the use of expensive TeO ₂ components. Therefore, the content of the TeO ₂ component is preferably 5.0%, more preferably less than 3.0%, and even more preferably less than 1.0%.
TeO ₂ component can use TeO ₂ or the like as a raw material.

The Sb ₂ O ₃ component is a component that accelerates the defoaming of the glass when it contains more than 0% and clarifies the glass, and is an optional component in the optical glass of the present invention. Sb ₂ O ₃ component, by a content relative to the glass total weight 1.0% or less, can be hardly caused excessive foaming during glass melting, _Sb 2 _{O 3} ingredient is dissolved facilities (especially Pt And the like can be made difficult to alloy. Therefore, the content of the Sb ₂ O ₃ component with respect to the total glass mass of the oxide-converted composition is preferably 1.0%, more preferably 0.8%, and still more preferably 0.6%. Here, from the viewpoint of easily obtaining an optical glass particularly low in solarization, the content of the glass total mass Sb ₂ O ₃ component of the oxide conversion composition is preferably 0.5%, more preferably 0.3%, most preferably Preferably, the upper limit is 0.1%.

Incidentally, components of the fining defoaming of glass is not limited to the above Sb ₂ O ₃ ingredients may be used known refining agents and defoamers in the field of glass production, or a combination thereof .

The sum (mass sum) of the contents of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is preferably 15.0% or less. Thereby, devitrification of glass can be reduced, an increase in the Abbe number can be suppressed, and the material cost of the glass can be reduced. Therefore, the mass sum of the Ln ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, and still more preferably 3.0% or less.

The sum (mass sum) of the contents of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 20.0% or less. Thereby, devitrification of the glass due to excessive inclusion of these components can be reduced. Therefore, the mass sum of the RO component is preferably 20.0% or less, more preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 7.0%, and even more preferably 5.0. %.
On the other hand, the mass sum of the RO component is preferably more than 0%, more preferably 1.0% or more, and still more preferably 2.0% or more, from the viewpoint of increasing the meltability of the glass raw material and reducing devitrification. It is good.

The sum (mass sum) of the contents of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na and K) is preferably 30.0% or less. Thereby, it is difficult to lower the refractive index of the glass, and devitrification at the time of glass formation can be reduced. Therefore, the total content of the Rn ₂ O component is preferably 30.0% or less, more preferably 28.0%, further preferably 25.0%, further preferably 20.0%, and more preferably 16.0. % Is the upper limit.
On the other hand, the mass sum of the Rn ₂ O component is preferably more than 0%, more preferably more than 5.0%, and still more preferably from the viewpoint of increasing the meltability of the glass raw material and lowering the glass transition point. It may be more than 0%, more preferably more than 10.0%.

<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.

[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, and the prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted, then a gold crucible, a platinum crucible In a platinum alloy crucible or iridium crucible, melt in a temperature range of 1000 to 1400 ° C. for 3 to 5 hours, stir and homogenize, blow out bubbles, etc., then lower the temperature to 900 to 1400 ° C. and then finish stirring This is done by removing the striae, casting into a mold and slow cooling.

<Physical properties>
The optical glass of the present invention preferably has a high refractive index and an Abbe number in a predetermined range.
The refractive index (n _d ) of the optical glass of the present invention is preferably 1.65, more preferably 1.68, and even more preferably 1.70. The upper limit of this refractive index is preferably 1.80, more preferably 1.78, even more preferably 1.77, and even more preferably 1.76.
The Abbe number (ν _d ) of the optical glass of the present invention is preferably 28, more preferably 30, and even more preferably 30.5. On the other hand, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 45, more preferably 43, more preferably 40, and still more preferably 38.
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 a low partial dispersion ratio (θg, F).
More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is (−0.00256 × νd + 0.637) ≦ (θg, F) ≦ with respect to the Abbe number (ν _d ). It is preferable to satisfy the relationship (−0.00256 × νd + 0.689).
Therefore, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (νd) preferably satisfy the relationship θg, F ≧ (−0.00256 × νd + 0.637), and θg, F It is more preferable to satisfy the relationship of ≧ (−0.00256 × νd + 0.647), and it is further preferable to satisfy the relationship of θg, F ≧ (−0.00256 × νd + 0.657).
On the other hand, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (νd) preferably satisfy the relationship θg, F ≦ (−0.00256 × νd + 0.689), and θg, It is more preferable to satisfy the relationship of F ≦ (−0.00256 × νd + 0.681), and it is further preferable to satisfy the relationship of θg, F ≦ (−0.00256 × νd + 0.677).
As a result, an optical glass having a low partial dispersion ratio (θg, F) can be obtained. Therefore, an optical element formed from the optical glass can be used to reduce chromatic aberration of the optical system.

In particular, in a region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of a general glass is higher than that of the normal line, the Abbe number (νd) on the horizontal axis and the partial value on the vertical axis. The relationship between the general glass partial dispersion ratio (θg, F) and the Abbe number (ν _d ) when the dispersion ratio (θg, F) is taken is represented by a curve having a larger slope than the normal line. In the relational expression of the partial dispersion ratio (θg, F) and Abbe number (νd) described above, by defining these relations using a straight line having a larger slope than the normal line, the partial dispersion ratio is higher than that of general glass. This means that a glass having a small (θg, F) can be obtained.

The optical glass of the present invention is preferably less colored.
In particular, when the optical glass of the present invention is expressed by the transmittance of the glass, the wavelength (λ ₈₀ ) exhibiting a spectral transmittance of 80% in a sample having a thickness of 10 mm is preferably 450 nm or less, more preferably 420 nm or less, and even more preferably. Is 410 nm or less, more preferably 400 nm or less.
In the optical glass of the present invention, a wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 365 nm or less, more preferably 355 nm or less, and further preferably 345 nm or less.
Thereby, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible region is enhanced. Therefore, this optical glass can be preferably used as a material for an optical element such as a lens.

  The optical glass of the present invention preferably has high devitrification resistance. Thereby, since the fall of the transmittance | permeability by crystallization of the glass at the time of glass preparation etc. is suppressed, this optical glass can be used preferably for the optical element which permeate | transmits visible lights, such as a lens. In particular, the optical glass of the present invention preferably has a low liquidus temperature of 1200 ° C. or lower. More specifically, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1200 ° C, more preferably 1150 ° C, more preferably 1100 ° C, more preferably 1050 ° C. As a result, even if the molten glass flows out at a lower temperature, crystallization of the produced glass is reduced, so that the devitrification resistance when the glass is formed from the molten state can be increased. The influence on the optical characteristics of the optical element can be reduced. On the other hand, the lower limit of the liquidus temperature of the optical glass of the present invention is not particularly limited, but the liquidus temperature of the glass obtained by the present invention is approximately 500 ° C. or higher, specifically 550 ° C. or higher, more specifically 600. Often above ℃. As used herein, “liquid phase temperature” refers to a glass sample pulverized to a particle size of about 2 mm on a platinum plate and held in a furnace with a temperature gradient from 800 ° C. to 1220 ° C. for 30 minutes. This is the lowest temperature at which no crystal is observed in the glass and devitrification does not occur, which is measured by observing the presence or absence of crystals in the glass with a microscope with a magnification of 80 after cooling.

  The optical glass of the present invention preferably has good press moldability. That is, it is preferable that devitrification and milky white do not occur before and after the reheating test (A). This makes it difficult for devitrification and coloring to occur even in a reheating test assuming reheat press processing, so that the light transmittance of the glass is less likely to be lost. Processing can be facilitated. That is, since an optical element having a complicated shape can be produced by press molding, it is possible to realize optical element production with low production cost and high productivity.

  Here, in the reheating test (A), a test piece of 15 mm × 15 mm × 30 mm is placed on an indented refractory and placed in an electric furnace and reheated, and the transition temperature (Tg) of each sample is 150 minutes from room temperature. The temperature is raised to a temperature higher than 100 ° C. to 120 ° C. (the temperature falling into the refractory), kept at that temperature for 30 minutes, then cooled to room temperature, taken out of the furnace, and the two opposing surfaces so that they can be observed inside After polishing to a thickness of 10 mm, the polished glass sample can be visually observed.

  It should be noted that the presence or absence of devitrification and milky white before and after the reheating test (A) can be confirmed, for example, visually, and that “devitrification and milky white do not occur” means, for example, after the reheating test (A) The value obtained by dividing the transmittance of light (d-line) having a wavelength of 587.56 nm of the test piece by the d-line transmittance of the test piece before the reheating test is approximately 0.80 or more.

[Preforms and optical elements]
A glass molded body can be produced from the produced optical glass by means of mold press molding such as reheat press molding or precision press molding. That is, a preform for mold press molding is prepared from optical glass, and after performing reheat press molding on the preform, polishing is performed to prepare a glass molded body, or for example, polishing is performed. The preform can be precision press-molded to produce a glass molded body. In addition, the means for producing the glass molded body is not limited to these means.

  The glass molded body thus produced is useful for various optical elements, and among them, it is particularly preferable to use it for applications of optical elements such as lenses and prisms. As a result, color bleeding due to chromatic aberration in the transmitted light of the optical system provided with the optical element is reduced. Therefore, when this optical element is used in a camera, a photographing object can be expressed more accurately, and when this optical element is used in a projector, a desired image can be projected with higher definition.

The compositions of Examples (No. 1 to No. 57) and Comparative Examples of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F), and spectral transmittance are 5 Tables 1 to 8 show the results of wavelengths (λ ₅ , λ ₈₀ ), liquid phase temperatures, and reheating tests (mold dropping tests) indicating% and 80%. The following examples are merely for illustrative purposes, and are not limited to these examples.

  The glasses of Examples and Comparative Examples are used as ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphate compounds, etc., as raw materials for the respective components. High-purity raw materials are selected, weighed so as to have the composition ratios of the examples and comparative examples shown in the table, and mixed uniformly, and then a stone crucible (platinum crucible, alumina depending on the melting property of the glass) It may be used in a crucible) and melted in a temperature range of 1100 to 1400 ° C. for 0.5 to 5 hours in an electric furnace according to the melting difficulty of the glass composition, then transferred to a platinum crucible and homogenized with stirring. After the foam was blown out, the temperature was lowered to 1000 to 1400 ° C., homogenized with stirring, cast into a mold, and slowly cooled to produce glass.

The refractive index (n _d ), Abbe number (ν _d ), and partial dispersion ratio (θg, F) of the glasses of 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 ₅ (wavelength when the transmittance was 5%) and λ ₈₀ (transmittance). Wavelength at 80%).

  The liquid phase temperatures of the examples and comparative examples were taken out after placing crushed glass samples on a platinum plate at intervals of 10 mm and holding them in a furnace with a temperature gradient between 800 ° C. and 1200 ° C. for 30 minutes. After cooling, the presence or absence of crystals in the glass sample was measured by observing with a microscope with a magnification of 80 times. At this time, the optical glass as a sample was pulverized into particles having a diameter of about 2 mm.

Moreover, about the glass of an Example and a comparative example, the presence or absence of devitrification and milky white before and after a reheating test was confirmed visually. Here, confirmation of devitrification and milky white before and after the reheating test is carried out by placing a test piece of 15 mm × 15 mm × 30 mm on a concave refractory and placing it in an electric furnace to reheat it to the reheating temperature. After being kept warm for 30 minutes, cooled to room temperature and taken out of the furnace, the opposing two surfaces were polished to a thickness of 10 mm so that they could be observed inside, and then visually checked for devitrification and milky white in the polished glass sample It was done by observing. At this time, devitrification and milk white do not occur when the reheating temperature is (Tg + 100 ° C. to 120 ° C.), and devitrification and also when the reheating temperature is higher than (Tg + 100 ° C. to 120 ° C.). For the glass in which no milk white was produced, the “reheating test” was set to “no devitrification”. Moreover, when the reheating temperature was set to a specific temperature within the range of (Tg + 100 ° C. to 120 ° C.), the glass that had devitrification or milk white had the “reheating test” “devitrified”.

As shown in these tables, in the optical glass of the example of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (νd) are (−0.00256 × νd + 0.637) ≦ (θg, F) ≦ ( −0.00256 × νd + 0.689), and more specifically, the relationship (−0.00256 × νd + 0.657) ≦ (θg, F) ≦ (−0.00256 × νd + 0.677) is satisfied. I met. That is, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) for the glass of the example of the present application is as shown in FIG.

Each of the optical glasses of the examples of the present invention has a refractive index (n _d ) of 1.65 or more, more specifically 1.67 or more, and this refractive index (n _d ) of 1.90 or less. Specifically, it was 1.80 or less, which was within a desired range.
The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 28 or more, more specifically 30 or more, and this Abbe number (ν _d ) of 45 or less, more specifically 39. And within the desired range.

In addition, the optical glasses of the examples of the present invention each had a λ ₈₀ (wavelength at 80% transmittance) of 450 nm or less, more specifically 420 nm or less.
In addition, in the optical glasses of the examples of the present invention, each of λ ₅ (wavelength at a transmittance of 5%) was 365 nm or less, more specifically, 355 nm or less.
Therefore, it became clear that the optical glass of the Example of this invention has the high transmittance | permeability with respect to visible light, and is hard to be colored.

In addition, the optical glass of the example of the present invention had a liquidus temperature of 1200 ° C. or lower, more specifically 1110 ° C. or lower.
Moreover, the optical glass of the Example of this invention was "no devitrification" in all the evaluation results of the reheating test. Therefore, it is presumed that the optical glass of the example of the present invention has high reheat press moldability because devitrification and milky white due to reheating are not angry.

  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 (9)

In mass% of oxide equivalent composition,
15.0-50.0% of SiO ₂ component,
25.0-50.0% of Nb ₂ O ₅ component,
Containing B ₂ O ₃ component 1.0-20.0%,
Optical glass in which devitrification and milky white do not occur before and after the reheating test (A).
[Reheating test (A): Reheating test pieces 15 mm × 15 mm × 30 mm, raising the temperature from room temperature to a temperature 100 ° C. to 120 ° C. higher than the transition temperature (Tg) of each sample in 150 minutes. The sample is kept at a temperature 100 ° C. to 120 ° C. higher than the glass transition temperature (Tg) for 30 minutes, then naturally cooled to room temperature, and the two opposing surfaces of the test piece are polished to a thickness of 10 mm and visually observed. ] In mass% of oxide equivalent composition,
ZnO component 0 to 25.0%,
ZrO ₂ component 0 to 20.0%,
The optical glass of claim 1. In mass% of oxide equivalent composition,
TiO ₂ component 0 to 15.0%,
WO ₃ component 0-10.0%,
MgO component 0 to 10.0%,
CaO component 0 to 10.0%,
SrO component 0 to 10.0%,
BaO component 0 to 10.0%,
La ₂ O ₃ component 0 to 10.0%,
Gd ₂ O ₃ component 0 to 10.0%,
Y ₂ O ₃ component 0 to 10.0%,
Yb ₂ O ₃ component 0 to 10.0%,
Li ₂ O component 0 to 20.0%,
Na ₂ O component 0 to 20.0%,
K ₂ O component 0 to 10.0%,
Ta ₂ O ₅ component 0 to 10.0%,
P ₂ O ₅ component 0 to 10.0%,
GeO ₂ component 0 to 10.0%,
Al ₂ O ₃ component 0 to 10.0%,
Ga ₂ O ₃ component 0 to 10.0%,
Bi ₂ O ₃ component 0 to 10.0%,
TeO ₂ components 0 to 5.0%, and SnO ₂ containing components 0 to 1.0% _Sb 2 _{O 3} component from 0 to 1.0%
The optical glass according to claim 1 or 2. The mass sum of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 0 to 15.0% by mass based on the oxide, and Rn ₂ The mass sum of the O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 0 to 30.0%, and the RO component (wherein R is Mg, Ca, Sr, Ba) The optical glass according to any one of claims 1 to 3, wherein the mass sum of (one or more selected from the group consisting of) is 0 to 20.0%.   The optical glass according to any one of claims 1 to 4, wherein the refractive index (nd) is 1.65 to 1.80, and the Abbe number (νd) is 28 to 45. 6. The optical glass according to claim 1, wherein a wavelength (λ ₈₀ ) exhibiting a spectral transmittance of 80% is 450 nm or less, and a wavelength (λ ₅ ) exhibiting a spectral transmittance of 5% is 365 nm or less.   An optical element made of the optical glass according to claim 1.   A preform for polishing and / or precision press molding comprising the optical glass according to any one of claims 1 to 6.   An optical apparatus comprising the optical element according to claim 7.

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