JP6509525B2 - Optical glass, preform and optical element - Google Patents

Description

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

  In recent years, digitalization and high definition of equipment using optical systems are rapidly progressing, and various optical equipment such as photographing equipment such as digital cameras and video cameras, and image reproduction (projection) equipment such as projectors and projection televisions In the field of optical systems, there is an increasing demand for reducing the number and weight of the entire optical system by reducing the number of optical elements such as lenses and prisms used in the optical system.

Among optical glasses for producing an optical element, it has a high refractive index (n _d ) of 1.80 or more and 2.20 or less, which can achieve weight reduction and miniaturization of the entire optical system, and is 20 or more and 35 The demand for high refractive index, high dispersion glasses having the following low Abbe numbers (ν _d ) is very high. As such a high refractive index and low dispersion glass, a glass composition as typified by Patent Document 1 is known.

Unexamined-Japanese-Patent No. 2010-030879

  In order to reduce the material cost of optical glass, it is desirable that the raw material cost of optical glass be as low as possible. However, the glass described in Patent Document 1 can not be said to sufficiently meet such a demand.

  On the other hand, even when the material cost of the optical glass is reduced, it is required that the stability of the optical glass is high and it is difficult to devitrify from the viewpoint of suppressing an increase in the manufacturing cost due to the decrease in productivity.

The present invention has been made in view of the above problems, and the object of the present invention is to have the refractive index (n _d ) and the Abbe number (v _d ) within the desired ranges and be stable. The purpose is to obtain high optical glass at lower cost.

The present inventors have intensively conducted researches to solve the above problems, and as a result, when the BaO component is used in combination with the B ₂ O ₃ component and the Ln ₂ O ₃ component, the desired high refractive index and It has been found that a glass having high stability can be obtained while the material cost can be suppressed while high dispersion can be obtained, and the present invention has been completed.
Specifically, the present invention provides the following.

(1) In terms of mole percent, B ₂ O ₃ component is 10.0% or more and 40.0% or less, Ln ₂ O ₃ component is 5.0% or more and 30.0% or less (wherein Ln is La, Gd, 1 or more selected from the group consisting of Y and Yb, and 1.0 to 20.0% of a BaO component, having a refractive index (nd) of 1.80 to 2.20, and 20 or more Optical glass having an Abbe number (νd) of 35 or less.

(2) in mol%,
0 to 30.0% of La ₂ O ₃ ingredients,
TiO ₂ component 0 to 50.0%,
SiO ₂ component 0 to 30.0% and ZrO ₂ component 0 to 20.0%
(1) The optical glass according to (1).

(3) in mol%,
0 to 15.0% of Gd ₂ O ₃ components,
0 to 30.0% of Y ₂ O ₃ components,
Yb ₂ O ₃ component 0 to 10.0%,
0 to 15.0% of Nb ₂ O ₅ component,
WO ₃ component 0 to 10.0%,
0 to 15.0% of MgO component,
0 to 15.0% of CaO ingredients,
0 to 15.0% of SrO component,
ZnO component 0 to 35.0%,
Li ₂ O component 0 to 10.0%,
Na ₂ O component 0 to 10.0%,
K ₂ O component 0 to 10.0%,
0 to 15.0% of P ₂ O ₅ components,
GeO ₂ component 0 to 15.0%,
Ta ₂ O ₅ components 0 to 10.0%,
Al ₂ O ₃ component 0 to 15.0%,
Bi ₂ O ₃ component 0 to 10.0%,
0 to 15.0% of TeO ₂ ingredients,
0 to 5.0% of SnO ₂ component and 0 to 1.0% of Sb ₂ O ₃ component
The optical glass as described in (1) or (2) which is.

(4) the molar sum _{(TiO 2 + Nb 2 O 5} + WO 3) is 60.0% or less 10.0% or more (1) to (3) any description of the optical glass.

(5) the molar ratio _{(TiO 2 + Nb 2 O 5} + WO 3) / Ln 2 O 3 is one wherein the optical glass of 0.50 or more 10.00 or less (1) to (4).

(6) the molar sum _{(B 2 O 3 + SiO 2} ) is less than equal to or more than 60.0% 20.0% (1) to (5) any description of the optical glass.

(7) the molar ratio _{(TiO 2 + BaO) / (} Ln 2 O 3 + Nb 2 O 5) is one wherein the optical glass of 0.50 or more 10.00 or less (1) to (6).

(8) The molar sum of RO component (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn) is 1.0% or more and 40.0% or less,
The optical according to any one of (1) to (7), wherein the molar sum of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na and K) is 10.0% or less Glass.

  (9) Any one of (1) to (8) according to any one of (1) to (8), wherein the refractive index (nd) and the Abbe number (νd) satisfy the relationship of (−0.02νd + 2.44) ≦ nd ≦ (−0.020.02d + 2.54) Optical glass.

  (10) Optical glass in any one of (1) to (9) whose specific gravity is 5.50 or less.

  (11) An optical element comprising the optical glass according to any one of (1) to (10).

  (12) A preform for polishing and / or precision press molding, which comprises the optical glass according to any one of (1) to (10).

  (13) An optical element formed by precision pressing the preform as described in (12).

According to the present invention, there refractive index (n _d) and Abbe number ([nu _d) is within a desired range, and can be a highly stable optical glass, it obtained cheaper.
Further, according to the present invention, while the refractive index (n _d) and Abbe number ([nu _d) is within the desired range, high transmittance for visible light, also and obtain a small optical glass having a specific gravity it can.

It is a figure which shows the relationship of the refractive index (nd) and Abbe's number ((nu) _d ) about the glass of the Example of this application.

The optical glass of the present invention is, in mol%, 10.0% to 40.0% of the B ₂ O ₃ component, and 5.0% to 30.0% 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, and 1.0 to 20.0% of a BaO component, and having a refractive index (nd) of 1.80 or more and 2.20 or less And have an Abbe number (νd) of 20 or more and 35 or less. According to the present invention, when a combination of BaO components in addition to the B ₂ O ₃ component and Ln ₂ O ₃ component, while obtained a desired high refractive index and high dispersion, is suppressed material costs, and, A highly stable glass can be obtained.

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

[Glass composition]
The composition range of each component which comprises the optical glass of this invention is described below. In the present specification, unless otherwise specified, the contents of the respective components are all represented by mol% with respect to the total mass of the glass in terms of the oxide equivalent composition. Here, “oxide conversion composition” is assumed that all oxides, composite salts, metal fluorides and the like used as raw materials of the glass component of the present invention are decomposed at the time of melting to change into oxides. It is the composition which described each ingredient contained in glass as 100 mol% of gross mass of the said formation oxide concerned.

<Required Component, Optional Component>
The B ₂ O ₃ component is an essential component indispensable as a glass-forming oxide in the optical glass of the present invention containing a large amount of rare earth oxide.
In particular, the devitrification resistance of the glass can be enhanced and the specific gravity can be reduced by containing the B ₂ O ₃ component at 10.0% or more. Therefore, the content of the B ₂ O ₃ component is preferably 10.0%, more preferably 13.0%, and still more preferably 16.0%.
On the other hand, when the content of the B ₂ O ₃ component is 40.0% or less, the decrease in refractive index and the increase in Abbe number can be suppressed, and the deterioration of the chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 40.0%, more preferably 38.0%, still more preferably 35.0%, further preferably 30.0%.
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 sum (molar sum) of the content of the Ln ₂ O ₃ component (wherein, Ln is one or more selected from the group consisting of La, Gd, Y, Yb) is 5.0% or more and 30.0% or less Is preferred.
In particular, by setting the molar sum to 5.0% or more, the refractive index of the glass can be increased, so that high refractive index glass can be easily obtained. Therefore, the molar sum of the content of the Ln ₂ O ₃ component is preferably 5.0%, more preferably 7.0%, still more preferably 9.0%.
On the other hand, by setting the molar sum to 30.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification resistance can be enhanced. Moreover, the rise in Abbe number can be suppressed by this, and the material cost of glass can be held down. Therefore, the molar sum of the content of the Ln ₂ O ₃ component is preferably 30.0%, more preferably 28.0%, still more preferably 25.0%, still more preferably 22.0%, further preferably 19 The upper limit is preferably 0. 0%, more preferably 14.0%.

By containing 1.0% or more of the BaO component, the material cost can be suppressed while the refractive index of the glass is increased, and the meltability and the devitrification resistance of the glass material can be improved. Therefore, the content of the BaO component is preferably 1.0%, more preferably 2.0%, still more preferably 3.5%, still more preferably 5.0%, still more preferably 7.5%, more preferably The lower limit is 8.0%.
On the other hand, by setting the content of the BaO component to 20.0% or less, it is possible to suppress the devitrification due to excessive content and the increase in specific gravity. Therefore, the upper limit of the content of the BaO component is preferably 20.0%, more preferably 18.0%, and still more preferably 15.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like can be used as a raw material.

The La ₂ O ₃ component is an optional component that can increase the refractive index when it contains more than 0%. Further, by containing a La ₂ O ₃ component, since the content of other rare earth elements to increase the specific gravity is reduced, it can more easily obtain a glass having a small specific gravity. Therefore, the content of the La ₂ O ₃ component is preferably more than 0%, more preferably 3.0%, still more preferably 5.0%, still more preferably 8.5%.
On the other hand, by setting the content of the La ₂ O ₃ component to 30.0% or less, the stability of the glass can be enhanced, the devitrification can be reduced, and the increase in Abbe number can be suppressed. Therefore, the content of the La ₂ O ₃ component is preferably 30.0%, more preferably 25.0%, still more preferably 20.0%, still more preferably 16.0%, still more preferably 14.0% Is the upper limit.
As the La ₂ O ₃ component, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The TiO ₂ component is an optional component capable of enhancing the refractive index, reducing the Abbe number, reducing the specific gravity, and improving the devitrification resistance, when the TiO ₂ component is contained. Therefore, the content of the TiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 5.0%, still more preferably more than 7.0%, still more preferably 12.0% More preferably, it is more than 16.0%, more preferably 20.5%, still more preferably 23.5%, still more preferably 24.5%, and even more preferably more than 25.4%. It is also good.
On the other hand, by setting the content of the TiO ₂ component to 50.0%, it is possible to reduce the coloration of the glass to enhance the visible light transmittance, and to suppress the Abbe's number more than necessary. Further, suppressing the devitrification due to excessive content of the TiO ₂ component. Therefore, the content of the TiO ₂ component is preferably 50.0%, more preferably 45.0%, still more preferably 40.0%, further preferably 35.0%.
TiO ₂ component can be used such as TiO ₂ as a raw material.

The SiO ₂ component is an optional component capable of increasing the viscosity of the molten glass, reducing the coloration of the glass, and enhancing the devitrification resistance, when it is contained in an amount of more than 0%. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 3.0%, still more preferably more than 6.0%, still more preferably 8.0% It may be more than 10.0%, more preferably more than 10.0%.
On the other hand, when the content of the SiO ₂ component is 30.0% or less, the decrease in the refractive index can be suppressed, the increase in the glass transition point can be suppressed, and the specific gravity can be reduced. Therefore, the content of the SiO ₂ component is preferably 30.0%, more preferably 25.0%, still more preferably 20.0%, further preferably 17.5%.
As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

The ZrO ₂ component is an optional component that can contribute to the increase in the refractive index of the glass and can improve the devitrification resistance when it contains more than 0%. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 2.0%, still more preferably more than 3.0%, still more preferably 4.0% It may be over.
On the other hand, by setting the ZrO ₂ component to 20.0% or less, it is possible to suppress an increase in Abbe number and a decrease in devitrification resistance due to an excessive content of the ZrO ₂ component. Therefore, the content of the ZrO ₂ component is preferably 20.0%, more preferably 15.0%, still more preferably 10.0%, further preferably 7.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The Y ₂ O ₃ component, the Gd ₂ O ₃ component and the Yb ₂ O ₃ component are optional components capable of enhancing the refractive index of the glass and enhancing the devitrification resistance, when at least one of them is contained in excess of 0%. is there.
On the other hand, the content of the Y ₂ O ₃ component is 30.0% or less, the content of the Gd ₂ O ₃ component is 15.0% or less, or the content of the Yb ₂ O ₃ component is By setting the content to 10.0% or less, devitrification due to excessive content can be reduced, and an increase in Abbe number can be suppressed. In particular, the material cost of the glass can be suppressed by reducing the content of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component. Therefore, the content of the Y ₂ O ₃ component is preferably 30.0% or less, more preferably less than 20.0%, and still more preferably less than 10.0%. Further, the content of the Gd ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 7.0%, still more preferably less than 4.0%, still more preferably Less than 2.0%. Further, the content of the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably less than 7.0%, still more preferably less than 4.0%, and still more preferably less than 2.0%.
As the Y ₂ O ₃ component, the Gd ₂ O ₃ component and the Yb ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , Yb ₂ O _{3 and the} like can be used as raw materials.

The Nb ₂ O ₅ component is an optional component that can increase the refractive index and lower the Abbe number, and can improve the devitrification resistance, when the Nb ₂ O ₅ content is more than 0%.
On the other hand, by setting the content of the Nb ₂ O ₅ component to 15.0% or less, the reduction of the devitrification resistance and the reduction of the visible light transmittance due to the excessive inclusion of the Nb ₂ O ₅ component are suppressed. Be In addition, this makes it possible to reduce the specific gravity of the glass and to reduce the material cost. Therefore, the content of the Nb ₂ O ₅ component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 5.0%, and still more preferably 3.34% or less.
For the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The WO ₃ component is an optional component which can increase the refractive index and lower the Abbe number, lower the glass transition temperature, and enhance the devitrification resistance, when the WO ₃ component is contained. Therefore, the content of WO ₃ ingredient is preferably 0 percent, more preferably from 0.1%, even more preferably may be higher than 0.3%.
On the other hand, by the content of WO ₃ components below 30.0%, it is difficult to reduce the transmittance of visible light of the glass, and suppress the material cost. 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 2.0%, and still more preferably less than 1.0%.
WO ₃ components, it is possible to use WO ₃ or the like as a raw material.

The MgO component, the CaO component and the SrO component are optional components capable of enhancing the meltability of the glass material and the devitrification resistance of the glass when containing at least any one of them in excess of 0%. In particular, the MgO component and the CaO component are components which can reduce the specific gravity by containing them.
On the other hand, by setting the content of each of the MgO component, the CaO component and the SrO component to 15.0% or less, it is possible to reduce the decrease in refractive index and the devitrification due to the excessive content of these components. Therefore, the content of each of the MgO component, the CaO component and the SrO component is preferably 15.0% or less, more preferably less than 10.0%, more preferably 8.5% or less, still more preferably 5.0% Less than.
As the MgO component, the CaO component and the SrO component, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as raw materials.

The ZnO component is an optional component capable of lowering the glass transition point, reducing the specific gravity and enhancing the chemical durability, when it is contained in excess of 0%. Therefore, the content of the ZnO component may be preferably more than 0%, more preferably more than 2.0%, still more preferably more than 4.0%, and still more preferably more than 7.0%.
On the other hand, lowering the refractive index and devitrification can be reduced by setting the content of the ZnO component to 35.0% or less. Moreover, since the viscosity of molten glass is raised by this, generation | occurrence | production of the striation to glass can be reduced. Therefore, the content of the ZnO component is preferably 35.0%, more preferably 30.0%, still more preferably 25.0%, still more preferably 20.0%, still more preferably 17.0%, more preferably The upper limit is 15.0%, more preferably 12.0%.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The Li ₂ O component is an optional component that can improve the meltability of the glass and lower the glass transition point when it contains more than 0%.
On the other hand, by making the content of the Li ₂ O component 10.0% or less, it is possible to reduce the decrease in refractive index and the devitrification, and to improve the chemical durability. Moreover, since the viscosity of molten glass is raised by this, generation | occurrence | production of the striation to glass can be reduced. Therefore, the content of the Li ₂ O 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 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 and the K ₂ O component are optional components capable of improving the meltability of the glass material, enhancing the devitrification resistance, and lowering the glass transition point when at least either of them is contained in excess of 0%. is there.
On the other hand, by making the content of each of the Na ₂ O component and the K ₂ O component 10.0% or less, it is possible to make it difficult to reduce the refractive index, and it is possible to reduce the devitrification due to excessive content. Therefore, the content of each of the Na ₂ O component and the K ₂ O component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.
As Na ₂ O component and K ₂ O component, use Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF ₃ , KHF ₂ , K ₂ SiF ₆ etc as raw materials. it can.

The P ₂ O ₅ component is an optional component capable of enhancing resistance to devitrification when it is contained in excess of 0%.
On the other hand, by setting the content of the P ₂ O ₅ component to 15.0% or less, it is possible to suppress the decrease in the chemical durability of the glass, particularly the water resistance. Therefore, the content of the P ₂ O ₅ component is preferably 15.0% or less, more preferably less than 10.0%, and still more preferably less than 5.0%.
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 enhancing the refractive index of the glass and enhancing the devitrification resistance when it contains more than 0%.
However, since GeO ₂ has a high raw material price, if the amount is large, the material cost will be high, and the cost reduction effect due to the inclusion of the BaO component and the like will be diminished. Therefore, the content of the GeO 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 1.0%, and most preferably do not do.
The GeO ₂ component can use GeO ₂ etc. as a raw material.

When the content of Ta ₂ O ₅ is more than 0%, it is an optional component that can increase the refractive index, the devitrification resistance, and the viscosity of the molten glass.
On the other hand, by setting the content of the Ta ₂ O ₅ component to 10.0% or less, the amount of use of the Ta ₂ O ₅ component, which is a rare mineral resource, is reduced, so that the material cost of glass can be reduced. Also, this makes it possible to reduce the specific gravity. 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 2.0%, and still more preferably less than 1.0%. Preferably it does not contain.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The Al ₂ O ₃ component is an optional component capable of enhancing the chemical durability and the devitrification resistance when it contains more than 0%.
On the other hand, by the content of the _Al 2 _{O 3} component to 15.0% can be reduced devitrification due to excessive containing. Therefore, the content of the Al ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, and still more preferably less than 5.0%.
As the Al ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF 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 to lower the Abbe number and lower the glass transition point, when the content is more than 0%.
On the other hand, when the content of the Bi ₂ O ₃ component is 10.0% or less, the devitrification resistance of the glass can be enhanced, and the coloration of the glass can be reduced to enhance the visible light transmittance. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0% or less, more preferably less than 8.0%, still more preferably less than 5.0%, and still more preferably less than 1.0%.
Bi ₂ O ₃ component can be used _Bi 2 _{O 3} and the like as raw materials.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when it contains more than 0%.
On the other hand, by making the content of the TeO ₂ component 15.0% or less, the coloration of the glass can be reduced and the visible light transmittance can be enhanced. Further, TeO ₂ has a problem that it can be alloyed with platinum when it melts a glass material in a crucible made of platinum or in a melting tank in which a 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%, and still more preferably less than 1.0%.
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 capable of enhancing the visible light transmittance of the glass while containing it by more than 0%, while reducing and reducing the oxidation of the molten glass.
On the other hand, by setting the content of the SnO ₂ component to 5.0% or less, coloring of the glass by reduction of the molten glass and devitrification of the glass can be reduced. Moreover, since the alloying of the SnO ₂ component and the melting equipment (especially noble metals such as Pt) is reduced, the life of the melting equipment can be prolonged. Therefore, the content of the SnO ₂ component is preferably 5.0%, more preferably 3.0%, and still more preferably 1.0%.
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 degassing the molten glass when it contains more than 0%.
On the other hand, when the amount of Sb ₂ O ₃ is too large, the transmittance in the short wavelength region of the visible light region is deteriorated. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.5%, and still more preferably 0.3%.
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 for clarifying and degassing the glass is not limited to the above-mentioned Sb ₂ O ₃ component, and a known clarifier and defoamer in the field of glass production, or a combination thereof can be used.

The sum (molar sum) of the content of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 10.0% or more and 60.0% or less.
In particular, by setting the sum to 10.0% or more, the refractive index is increased, the Abbe number is decreased, and the stability of the glass is increased. Therefore, it is possible to easily obtain an optical glass having a high refractive index and a high dispersion. Therefore, the molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 10.0% or more, more preferably more than 12.0%, still more preferably more than 16.0%, still more preferably more than 20.0% More preferably, it is 23.5% or more, more preferably 25.7% or more.
On the other hand, by setting the sum to 60.0% or less, coloring and devitrification of the glass due to excessive inclusion of these components can be reduced. Therefore, the molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 60.0%, more preferably 50.0%, still more preferably 45.0%, still more preferably 40.0%, still more preferably The upper limit is 38.0%.

Content of TiO ₂ component, Nb ₂ O ₅ component and WO ₃ component relative to the content of Ln ₂ O ₃ component (wherein, L n is one or more selected from the group consisting of La, Gd, Y, Yb) The ratio (molar ratio) of the sum of is preferably 0.50 or more and 10.00 or less.
In particular, by setting the ratio to 0.50 or more, the refractive index is increased, the Abbe number is decreased, and the stability of the glass is increased, so that it is possible to easily obtain an optical glass having a high refractive index and a high dispersion. Therefore, the molar ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ is preferably 0.50, more preferably 0.65, still more preferably 0.80, still more preferably 1.10, more preferably Has a lower limit of 1.35, more preferably 1.65, further preferably 1.85.
On the other hand, by making this ratio 10.00 or less, the devitrification resistance can be enhanced, and the transmittance in the short wavelength region of the visible light region can be enhanced. Therefore, the molar ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ is preferably 10.00, more preferably 7.00, and still more preferably 4.00.

The sum (molar sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 20.0% or more and 60.0% or less.
In particular, the devitrification due to the deficiency of the B ₂ O ₃ component and the SiO ₂ component can be suppressed by setting the sum to 20.0% or more. Therefore, the molar sum (B ₂ O ₃ + SiO ₂ ) is preferably 20.0%, more preferably 25.0%, still more preferably 29.0%, still more preferably 34.0%, further preferably 38. The lower limit is 0%.
On the other hand, by setting the sum to 60.0% or less, it is possible to suppress the decrease in refractive index due to the excessive inclusion of these components. Therefore, the molar sum (B ₂ O ₃ + SiO ₂ ) is preferably 60.0%, more preferably 50.0%, still more preferably 46.0%, still more preferably 43.0%, still more preferably 41. The upper limit is 0%.

The optical glass of the present invention comprises TiO 2 with respect to the 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) and the Nb ₂ O ₅ component. It is preferable that the ratio (molar ratio) of the sum of the contents of the _two components and the BaO component is 0.50 or more and 10.00 or less.
In particular, by setting this ratio to 0.50 or more, among the components that increase the refractive index, the content of the inexpensive TiO ₂ component and BaO component of the material cost increases relatively, thereby reducing the material cost of the glass. it can. This also enhances the stability of the glass while obtaining the desired high refractive index and high dispersion. Therefore, the molar ratio (TiO ₂ + BaO) / (Ln ₂ O ₃ + Nb ₂ O ₅ ) is preferably 0.50, more preferably 0.80, still more preferably 1.00, still more preferably 1.30, further The lower limit is preferably 1.60, more preferably 2.00, more preferably 2.50, and still more preferably 2.65.
On the other hand, by making this ratio 10.00 or less, the devitrification of the glass by this ratio being too large can be reduced. Therefore, the molar ratio (TiO ₂ + BaO) / (Ln ₂ O ₃ + Nb ₂ O ₅ ) is preferably 10.00, more preferably 8.00, and still more preferably 6.00.

The sum (molar sum) of the content of the RO component (wherein R is one or more selected from the group consisting of Zn, Mg, Ca, Sr, and Ba) is 1.0% or more and 40.0% or less preferable.
In particular, by making the sum 1.0% or more, the melting property of the glass material and the devitrification resistance of the glass can be enhanced. Therefore, the total content of the RO component is preferably 1.0%, more preferably 5.0%, still more preferably 8.0%, still more preferably 11.0%, still more preferably 13.0%. I assume.
On the other hand, when the sum is 40.0% or less, devitrification due to excessive inclusion of these components can be reduced, and a decrease in refractive index can be suppressed. Therefore, the total content of the RO component is preferably 40.0%, more preferably 35.0%, still more preferably 30.0%, further preferably 25.0%.

The sum (molar sum) of the content of the Rn ₂ O component (wherein, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 10.0% or less. Thereby, the decrease in the refractive index of the glass can be suppressed and the devitrification can be reduced. Therefore, the molar sum of the content of the Rn ₂ O component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%.

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

  Other components can be added as needed as long as the properties of the glass of the present invention are not impaired. However, each transition metal component such as Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu excluding V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo is independent. In the case of an optical glass using a wavelength in the visible range, it is preferable that the glass be substantially free of light, because the glass is colored even when contained in a small amount in a complex or causes absorption at a specific wavelength in the visible range. .

Further, lead compounds and As ₂ O ₃ or the like arsenic compound such as PbO, because environmental load is highly components, it does not substantially contained, i.e., it is desirable not to contain any except inevitable contamination.

  Furthermore, Th, Cd, Tl, Os, Be, and Se components tend to refrain from use as harmful chemical substances in recent years, and they are not only used in glass manufacturing processes but also in processing processes and disposal after productization. All environmental measures are needed. Therefore, when emphasizing environmental impact, it is preferable not to contain these substantially.

[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, and then a platinum crucible and a platinum alloy Put in a crucible or iridium crucible, melt in a temperature range of 1100 to 1400 ° C for 3 to 5 hours, stir and homogenize, perform foam breakage, etc., lower to a temperature of 1000 to 1300 ° C and then finish agitate and pulse It is manufactured by removing the waste, casting in a mold and annealing.

<Physical properties>
The optical glass of the present invention has a high refractive index and a high Abbe number (low dispersion).
In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.80, more preferably 1.85, and still more preferably more than 1.87, more preferably more than 1.90. The upper limit of the refractive index may be preferably 2.20, more preferably 2.10, still more preferably 2.05, and still more preferably 1.99. The Abbe number (ν _d ) of the optical glass of the present invention is preferably 20, more preferably 22, still more preferably 24 as a lower limit, preferably 35, more preferably 34, still more preferably 32 as an upper limit. More preferably, it is less than 30.
Since the optical glass of the present invention has such refractive index and Abbe number, it is useful for optical design, and the optical system can be miniaturized while achieving particularly high imaging characteristics etc. Can expand the degree of freedom of

Here, in the optical glass of the present invention, it is preferable that the refractive index (nd) and the Abbe number (vd) satisfy the relationship of (-0.02 vd + 2.44) <nd <(-0.02 vd + 2.54). In the glass having the composition specified in the present invention, more stable glass can be obtained when the refractive index (nd) and the Abbe number (vd) satisfy this relationship.
Therefore, in the optical glass of the present invention, it is preferable that the refractive index (nd) and the Abbe number (νd) satisfy the relationship of nd ≧ (−0.02νd + 2.44), and nd ≧ (−0.02νd + 2.45) It is more preferable to satisfy the relation of nd さ ら に (−0.02 dd + 2.46).
On the other hand, in the optical glass of the present invention, the refractive index (nd) and the Abbe number (νd) preferably satisfy the relationship of nd ≦ (−0.02 0.02d + 2.54), and nd ≦ (−0.02 dd + 2. It is more preferable to satisfy the relation of 53), and it is further preferable to satisfy the relation of nd ≦ (−0.02 vd + 2.52)).

The optical glass of the present invention preferably has a high visible light transmittance, particularly high light transmittance on the short wavelength side of visible light, whereby the coloration is low.
In particular, the optical glass of the present invention preferably has a wavelength (λ ₇₀ ) of 600 nm, more preferably 550 nm, still more preferably 520 nm, which exhibits a spectral transmittance of 70% for a sample of 10 mm thickness, as represented by the transmittance of glass. It is an upper limit.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% for a sample with a thickness of 10 mm is preferably 400 nm, more preferably 390 nm, further preferably 380 nm.
As a result, the absorption edge of the glass is in the vicinity of the ultraviolet region, and the transparency of the glass to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element that transmits light such as a lens.

The optical glass of the present invention preferably has a small specific gravity. More specifically, the specific gravity of the optical glass of the present invention is preferably 5.50 or less. As a result, the mass of the optical element and the optical apparatus using the same is reduced, which can contribute to the weight reduction of the optical apparatus. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.50, more preferably 5.20, still more preferably 5.00, still more preferably 4.80. The specific gravity of the optical glass of the present invention is often about 3.00 or more, more specifically 3.50 or more, and further more specifically 4.00 or more.
The specific gravity of the optical glass of the present invention is measured based on Japan Optical Glass Industrial Standard JOGIS 05-1975 "Method of measuring specific gravity of optical glass".

  The optical glass of the present invention is preferably a stable glass having high resistance to devitrification (sometimes referred to simply as “resistance to devitrification” in the specification) at the time of production of the glass. Thereby, since the fall of the transmittance | permeability by crystallization of glass at the time of glass preparation, etc. is suppressed, this optical glass can be preferably used for the optical element which permeate | transmits visible light, such as a lens. In addition, as a scale which shows that devitrification resistance at the time of glass preparation is high, it can be mentioned that liquidus temperature is low, for example.

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

  Thus, although the glass molded object formed from the optical glass of this invention is useful for various optical elements and optical design, it is preferable to use for optical elements, such as a lens and a prism, especially among these. As a result, it becomes possible to form a glass molded body having a large diameter, and thus while achieving upsizing of the optical element, high definition and high precision imaging characteristics and projection when used in an optical apparatus such as a camera or a projector Characteristics can be realized.

The compositions of the examples (No. 1 to No. 65) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), wavelengths (λ ₅ , λ showing a spectral transmittance of 5% and 70%) ₇₀ ) and specific gravity are shown in Tables 1 to 9.
The following examples are for the purpose of illustration only, and the present invention is not limited to these examples.

  The glasses of the examples have high purity, which are used for ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc., each of which is a raw material of each component. The raw materials were selected, weighed and uniformly mixed so that the proportions of the compositions of the respective examples and comparative examples shown in the table were obtained, and then charged into a platinum crucible, and an electric furnace according to the melting difficulty of the glass composition The solution is melted at 1100-1400 ° C for 3 to 5 hours, stirred, homogenized and defoamed, etc., then the temperature is lowered to 1000-1300 ° C, stirred and homogenized, and then cast in a mold and slowly cooled. The glass was made.

The refractive index (n _d ) and the Abbe number (ν _d ) of the glasses of the examples were measured based on the Japan Optical Glass Industrial Standard JOGIS 01-2003. Then, from the values of the refractive index (n _d ) and the Abbe number ( _{d d} ), the intercept b when the slope a is 0.02 in the relational expression n _d = −a × ν _d + b is obtained.
In addition, the glass used for this measurement used what was processed by the slow cooling furnace, making the slow cooling temperature-fall rate into -25 degreeC / hr.

The transmittance of the glass of the example was measured according to Japan Optical Glass Industrial Standard JOGIS02. In the present invention, the transmittance of glass was measured to determine the presence or absence and degree of coloring of the glass. Specifically, according to thickness of 10 ± 0.1 mm of the face parallel abrasive article in JISZ8722, and measuring the spectral transmittance of 200 to 800 nm, lambda ₅ (wavelength when the transmittance 5%) and lambda ₇₀ (transmittance The wavelength of 70%) was determined.

  The specific gravity of the glass of the example was measured based on Japan Optical Glass Industrial Standard JOGIS 05-1975 "Method of measuring specific gravity of optical glass".

As shown in these tables, all the optical glasses of the examples of the present invention have a refractive index (n _d ) of 1.80 or more, more specifically 1.90 or more, and the refractive index (n _d ) is 2.20 or less, more specifically 1.99 or less, and within the desired range.

The optical glasses according to the examples of the present invention each have an Abbe number (v _d ) of 20 or more, more specifically 25 or more, and this Abbe number (v _d ) is 35 or less, more specifically 30. It was below and was within the desired range.

In the optical glass of the embodiment of the present invention, the refractive index (nd) and the Abbe number (vd) satisfy the relationship of (-0.02 vd + 2.44) <nd <(-0.02 vd + 2.54). More specifically, the relationship of (−0.02 vd + 2.47) ≦ nd ≦ (−0.02 vd + 2.51) was satisfied. Then, the relationship between the refractive index (nd) and the Abbe number (vd) for the glass of the example of the present application is as shown in FIG.
All of these optical glasses were stable glasses which were not devitrified.
For this reason, when the optical glass of the embodiment of the present invention contains a BaO component whose material cost is low among the components contributing to the high refractive index, the refractive index (n _d ) and the Abbe number (ν _d ) are desired. It has been revealed that an optical glass having a high stability can be obtained.

  The optical glasses of the examples of the present invention all had a specific gravity of 5.50 or less, more specifically, 5.00 or less, and were within the desired range.

Moreover, as for the optical glass of the Example of this invention, (lambda) ₇₀ (wavelength at the time of the transmittance | permeability 70%) of all was 600 nm or less, more specifically 520 nm or less. Moreover, as for the optical glass of the Example of this invention, (lambda) ₅ (wavelength at 5% of transmittance | permeability) of all was 400 nm or less, more specifically, 375 nm or less. For this reason, it became clear that the optical glass of the Example of this invention has high transmittance | permeability with respect to visible light, and is hard to color.

Therefore, the optical glass of the embodiment of the present invention has a refractive index (n _d ) and an Abbe number (v _d ) within the desired ranges, high stability, high transmittance for visible light, and specific gravity. It has been found that small optical glasses can be obtained more inexpensively.

  Although the present invention has been described in detail for the purpose of illustration, the present embodiment is for the purpose of illustration only, 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 (10)

In terms of mole percent, B ₂ O ₃ component is 10.0% or more and 40.0% or less, Ln ₂ O ₃ component is 5.0% or more and 30.0% or less (in the formula, Ln is La, Gd, Y, Yb And 3.5 to 20.0% of BaO components, and one or more selected from the group consisting of
WO ₃ ingredients more than 0.3 % to 10.0%,
The molar sum (B ₂ O ₃ + SiO ₂ ) is 29.0% or more and 60.0% or less,
The molar ratio (TiO ₂ + BaO) / (Ln ₂ O ₃ + Nb ₂ O ₅ ) is 2.00 or more and 10.00 or less,
An optical glass having a refractive index (nd) of 1.80 to 2.20 and an Abbe number (ア ッ d) of 20 to 35. In mol%,
0 to 30.0% of La ₂ O ₃ ingredients,
TiO ₂ component 0 to 50.0%,
SiO ₂ component 0 to 30.0% and ZrO ₂ component 0 to 20.0%
The optical glass according to claim 1, which is The optical glass according to claim 1 or 2, wherein the molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 10.0% or more and 60.0% or less. Molar ratio _{(TiO 2 + Nb 2 O 5} + WO 3) / Ln 2 O 3 is 0.50 or more 10.00 or less any description of the optical glass of claims 1 3. 1.0% or more and 40.0% or less of the molar sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, Ba, and Zn),
Rn ₂ O component (wherein, Rn is Li, Na, 1 or more selected from the group consisting of K) optical glass according to any one of claims 1 to 4 mol sum is less than or equal to 10.0%. The optical glass according to any one of claims 1 to 5 , wherein the refractive index (nd) and the Abbe number (νd) satisfy the relationship of (-0.02 vd + 2.44) nd nd ≦ (-0.02 v d + 2.54). The optical glass according to any one of claims 1 to 6 , which has a specific gravity of 5.50 or less. An optical element comprising the optical glass according to any one of claims 1 to 7 . A preform for polishing and / or precision press molding comprising the optical glass according to any one of claims 1 to 7 . An optical element formed by precision pressing the preform according to claim 9 .

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