WO2013094619A1 - Optical glass and optical element - Google Patents

Abstract

The invention provides, at low cost, glass that has high resistance to devitrification while the index of refraction (n_d) and the Abbe number (ν_d) thereof lie within a desired range. Optical glass includes 1.0 to 30.0% of a B₂O₃ component and 10.0 to 60.0% of a La₂O₃ component by mass%. Preferably, this optical glass has an index of refraction (n_d) of at least 1.75 and has an Abbe number (ν_d) between 23 and 50.

Description

Optical glass and optical element

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

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

Among optical glasses for producing optical elements, in particular, it has a refractive index (n _d ) of 1.75 or more and an Abbe number of 23 or more and 50 or less (which can reduce the weight and size of the entire optical system). There is a great demand for high refractive index, low dispersion glass with ν _d ). As such a high refractive index and low dispersion glass, glass compositions represented by Patent Documents 1 to 8 are known.

JP 2006-016293 A Japanese Patent Application Laid-Open No. 2011-144069 JP 2010-083705 A JP 2008-001551 A JP 2001-348244 A JP 2009-173520 A JP 2003-267748 A JP 2006-240889 A

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.

Also, in order to reduce the material cost of the optical glass, it is desired that the raw material costs of the components constituting the optical glass are as low as possible. Moreover, in order to reduce the manufacturing cost of optical glass, it is desired that the raw material has high meltability and is melted at a lower temperature. However, it is difficult to say that the glasses described in Patent Documents 1 to 8 sufficiently meet such requirements.

In particular, the glasses described in Patent Documents 1 and 2 have a problem that the specific gravity of the glass is large and the mass of the optical element is large. That is, when these glasses are used in optical devices such as cameras and projectors, there is a problem that the mass of the entire optical device tends to increase.

The present invention has been made in view of the above problems, and its object is to provide resistance to devitrification while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges. It is to obtain a glass having a high and high stability at a lower cost.

Another object of the present invention is to obtain glass that can contribute to weight reduction of optical equipment.

In order to solve the above-mentioned problems, the present inventors have conducted intensive test studies. As a result, in a glass containing B ₂ O ₃ component and La ₂ O ₃ component as essential components, a desired high refractive index and high Abbe. The inventors have found that the material cost of glass can be reduced while obtaining a stable glass having a number, and have completed the present invention.

In addition, the present inventors include a glass containing B ₂ O ₃ component and La ₂ O ₃ component as essential components. By placing the content of the Y ₂ O ₃ component within a predetermined range, the desired high refraction can be achieved. It has also been found that the glass material cost is reduced and the specific gravity of the glass is reduced while a stable glass having a high ratio and a high Abbe number is obtained.

In addition, the present inventors reduced the content of the Gd ₂ O ₃ component in the glass containing the B ₂ O ₃ component and the La ₂ O ₃ component, thereby allowing a stable glass having a desired refractive index and Abbe number. It has also been found that the material cost of glass can be reduced.

In addition, the present inventors reduced the content of the Ta ₂ O ₅ component to a glass having an Abbe number of 35 or more by containing the B ₂ O ₃ component and the La ₂ O ₃ component, thereby reducing the desired content. It has also been found that the glass material cost is reduced and the liquidus temperature of the glass is lowered while having a refractive index and an Abbe number.
Specifically, the present invention provides the following.

(1)% by weight _B 2 _{O 3} ingredient 1.0 to 30.0% and _La 2 _{O 3} component from 10.0 to 60.0% content for optical glass.

(2) The optical glass according to (1), wherein the content of the Ta ₂ O ₅ component is 15.0% by mass or less.

(3) The optical glass according to (1) or (2), which has an Abbe number (ν _d ) of 35 or more and a Ta ₂ O ₅ component content of less than 15.0%.

(4) The optical glass according to any one of (1) to (3), wherein the content of the Y ₂ O ₃ component is 30.0% by mass or less.

(5) The optical glass according to any one of (1) to (4), wherein the Gd ₂ O ₃ component content is 40.0% by mass or less.

(6) The optical glass according to any one of (1) to (5), wherein the Gd ₂ O ₃ component content is 20.0% by mass or less.

(7) The optical glass according to any one of (1) to (6), wherein the content of the Yb ₂ O ₃ component is 20.0% by mass or less.

(8) 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 30.0% or more and 75.0% or less (1 ) To (7).

(9) _Ln 2 _{O 3} component (wherein, Ln is La, Gd, Y, 1 or more selected from the group consisting of Yb) mass sum is less than 75.0% or more 35.0% (1 ) To (8).

(10) 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 30.0% or more and 70.0% or less (1 ) To (9).

(11) The optical glass according to any one of (1) to (10), wherein the mass ratio (Gd ₂ O ₃ + Yb ₂ O ₃ ) / (La ₂ O ₃ + Y ₂ O ₃ ) is 0.50 or less.

(12) The optical glass according to any one of (1) to (11), wherein the sum of the contents of the Gd ₂ O ₃ component, the Yb ₂ O ₃ component, and the Ta ₂ O ₅ component is 30.0% or less.

(13) The optical glass according to any one of (1) to (12), wherein the sum of the contents of the Gd ₂ O ₃ component, the Yb ₂ O ₃ component, and the Ta ₂ O ₅ component is 20.0% or less.

(14) TiO ₂ component in mass% 0 to 30.0%
Nb ₂ O ₅ component 0-20.0%
WO ₃ component 0-25.0%
The optical glass according to any one of (1) to (13).

(15) By weight% WO ₃ component 0-25.0%
Nb ₂ O ₅ component 0-20.0%
TiO ₂ component 0-30.0%
The optical glass according to any one of (1) to (14).

(16) The optical glass according to any one of (1) to (15), wherein the content of the TiO ₂ component is 20.0% or less by mass.

(17) TiO ₂ component in mass% 0 to 15.0%
Nb ₂ O ₅ component 0-20.0%
WO ₃ component 0-20.0%
The optical glass according to any one of (1) to (16).

(18) The optical glass according to any one of (1) to (17), wherein the sum of the contents of the Nb ₂ O ₅ component and the WO ₃ component is 1.0% or more and 30.0% or less.

(19) The optical glass according to any one of (1) to (18), wherein the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is 30.0% or less.

(20) The optical glass according to any one of (1) to (19), wherein the content of the SiO ₂ component is 30.0% or less by mass%.

(21) The optical glass according to any one of (1) to (20), wherein the content of the SiO ₂ component is 20.0% by mass or less.

(22) The optical glass according to any one of (1) to (21), wherein the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 1.0% or more and 30.0% or less.

(23) The optical glass according to any one of (1) to (22), wherein the mass ratio (Nb ₂ O ₅ + WO ₃ ) / (B ₂ O ₃ + SiO ₂ ) is 0.15 or more and 2.00 or less.

(24) MgO component by mass% 0-20.0%
CaO component 0-20.0%
SrO component 0-20.0%
BaO component 0-25.0%
The optical glass according to any one of (1) to (23).

(25) MgO component by mass% 0 to 10.0%
CaO component 0-10.0%
SrO component 0 ～ 10.0%
BaO component 0-25.0%
The optical glass according to any one of (1) to (24).

(26) Any of (1) to (25), wherein the mass sum of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 25.0% or less The optical glass described.

(27) The optical glass according to any one of (1) to (26), wherein the content of the Li ₂ O component is 10.0% by mass or less.

(28) Na ₂ O component by mass% 0 to 10.0%
K ₂ O component 0-10.0%
Cs ₂ O component 0 to 10.0%
The optical glass according to any one of (1) to (27).

(29) Rn ₂ O component (wherein, Rn is Li, Na, K, 1 or more selected from the group consisting of Cs) from the mass sum is less than or equal to 15.0% (1) (28) Any one of the optical glasses.

(30) The optical glass according to any one of (1) to (29), wherein the ZnO component content is 25.0% or less by mass%.

(31) The optical glass according to any one of (1) to (30), wherein the ZnO component content is 15.0% or less by mass%.

(32) P ₂ O ₅ component by mass% 0 to 10.0%
GeO ₂ component 0 ～ 10.0%
ZrO ₂ component 0 ～ 15.0%
ZnO component 0-15.0%
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 component 0-20.0%
SnO ₂ component 0-1.0%
Sb ₂ O ₃ component 0-1.0%
The optical glass according to any one of (1) to (31).

(33) The optical glass according to any one of (1) to (32), which has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 23 to 50.

(34) The optical glass according to any one of (1) to (33), which has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 35 or more and 50 or less.

(35) The optical glass according to any one of (1) to (34), which has a liquidus temperature of 1300 ° C. or lower.

(36) An optical element using the optical glass described in any one of (1) to (35) as a base material.

(37) An optical device comprising the optical element described in (36).

According to the present invention, a glass having high devitrification resistance and stability can be obtained at a lower cost while the refractive index (n _d ) and Abbe number (ν _d ) are within the desired ranges.

Moreover, according to the present invention, it is possible to obtain glass that can contribute to weight reduction of the optical device.

The optical glass of the present invention, oxides by mass% with respect to the glass the total weight of the composition in terms _of, B 2 _{O 3} component from 1.0 to 30.0% and content _{of La} 2 _{O 3} component from 10.0 to 60.0% To do. By containing the La ₂ O ₃ component as an essential component and keeping the content of other components within a predetermined range, the amount of expensive components such as Gd ₂ O ₃ and Ta ₂ O ₅ can be reduced. However, a high refractive index and Abbe number can be obtained, and an increase in the liquidus temperature can be suppressed. Therefore, it is possible to obtain an optical glass having a high devitrification resistance and a stable optical glass at a lower cost while the refractive index and the Abbe number are within the desired ranges.

Of these, the first optical glass, oxides by mass% with respect to the glass the total weight of the composition in terms _of, B 2 _{O 3} component from 1.0 to 30.0% and _La 2 _{O 3} component from 10.0 to 60. 0% is contained, and the content of the Y ₂ O ₃ component is 30.0% or less. By containing the La ₂ O ₃ component as an essential component and making the content of the Y ₂ O ₃ component within a predetermined range, rare earth elements that are expensive and often increase the specific gravity of the glass, particularly Gd ₂ Even if O ₃ or Yb ₂ O ₃ is reduced, a high refractive index and Abbe number can be obtained, and an increase in the liquidus temperature can be suppressed. Therefore, an optical glass with high devitrification resistance that has a refractive index of 1.75 or more and an Abbe number of 23 or more and 50 or less but has a small specific gravity and can contribute to weight reduction of an optical device is obtained at a lower cost. be able to.

The second optical glass has a B ₂ O ₃ component of 1.0 to 30.0% and a La ₂ O ₃ component of 10.0 to 60% by mass with respect to the total mass of the glass having an oxide equivalent composition. containing 2.0%, the content of _Gd 2 _{O 3} component is less 20.0%. By reducing the content of Gd ₂ O ₃ component, to reduce the amount of the particular expensive Gd ₂ O ₃ component among the rare earth elements, the raw material cost of the optical glass is reduced. At the same time, even if the Gd ₂ O ₃ component is reduced by using the B ₂ O ₃ component and the La ₂ O ₃ component as a base, it has a refractive index of 1.75 or more and an Abbe number of 30 to 50. However, the liquidus temperature of the glass tends to be low. Therefore, a stable optical glass having a refractive index and an Abbe number within a desired range and having high devitrification resistance and an optical element using the same can be obtained at a lower cost.

The third optical glass, 1.0 to 30.0% of _B 2 _{O 3} component in mass% and _La 2 _{O 3} ingredients 10.0 contains to 60.0%, more than 35 Abbe number ( ν _d ) and the content of the Ta ₂ O ₅ component is less than 15.0%. By reducing the content of Ta ₂ O ₅ component, the amount of Ta ₂ O ₅ component requiring melting for expensive and high temperature to reduce the raw material cost and manufacturing cost of the optical glass is reduced. At the same time, by using the B ₂ O ₃ component and the La ₂ O ₃ component as a base, the liquidus temperature tends to be low while having an Abbe number (ν _d ) of 35 or more. Therefore, while the refractive index (n _d) and Abbe number ([nu _d) is within the desired range, and high optical glass devitrification resistance, it is possible to obtain an optical device using the same more expensive.

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

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

<About essential and optional components>
The B ₂ O ₃ component is an essential component that is indispensable as a glass-forming oxide.
In particular, by containing 1.0% or more of the B ₂ O ₃ component, the devitrification resistance of the glass can be enhanced and the dispersion of the glass can be reduced. Therefore, the content of the B ₂ O ₃ component is preferably 1.0%, more preferably 3.0%, still more preferably 5.0%, still more preferably 8.5%, and even more preferably 10.5%. Is the lower limit.
On the other hand, by making the content of the B ₂ O ₃ component 30.0% or less, a larger refractive index can be easily obtained, and deterioration of chemical durability can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 30.0%, more preferably 25.0%, even more preferably 20.0%, still more preferably 18.0%, still more preferably 16.4%. Is the upper limit.
As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ .10H ₂ O, BPO ₄ or the like can be used as a raw material.

The La ₂ O ₃ component is a component that increases the refractive index of the glass and decreases the dispersion (increases the Abbe number). In particular, a desired high refractive index can be obtained by containing 10.0% or more of the La ₂ O ₃ component. Accordingly, the content of the La ₂ O ₃ component is preferably 10.0%, more preferably 20.0%, still more preferably 25.0%, still more preferably 26.0%, and even more preferably 30.0%. More preferably, the lower limit is 34.0%, more preferably 35.0%, and still more preferably 39.0%.
On the other hand, the devitrification resistance of the glass can be increased by setting the content of the La ₂ O ₃ component to 60.0% or less. Accordingly, the content of the La ₂ O ₃ component is preferably 60.0%, more preferably 58.0%, even more preferably 56.0%, still more preferably 55.0%, and even more preferably 50.0%. 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 Y ₂ O ₃ component is an optional component that can suppress the material cost of the glass and reduce the specific gravity while maintaining a high refractive index and a high Abbe number when it contains more than 0%. This Y ₂ O ₃ component is useful for the optical glass of the present invention because the material cost is low among the rare earth elements and the specific gravity is easily reduced as compared with other rare earth elements. Therefore, the content of the Y ₂ O ₃ component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 0.5%, still more preferably more than 1.0%, still more preferably 1. It may be more than 0%.
On the other hand, by setting the content of the Y ₂ O ₃ component to 30.0% or less, a decrease in the refractive index of the glass can be suppressed and the devitrification resistance of the glass can be enhanced. Accordingly, the upper limit of the content of the Y ₂ O ₃ component is preferably 30.0%, more preferably 25.0%, even more preferably 20.0%, and even more preferably 15.0%.
As the Y ₂ O ₃ component, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

Gd ₂ O ₃ component, when 0% ultra containing increasing refractive index of the glass, which is an optional component and increased the Abbe number.
On the other hand, by reducing the particularly expensive Gd ₂ O ₃ component among rare earth elements to 40.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be produced. Moreover, this can suppress the increase of the Abbe number of the glass more than necessary. Therefore, the content of the Gd ₂ O ₃ component is preferably 40.0%, more preferably 30.0%, still more preferably 20.0%, still more preferably 15.0%, and even more preferably 10.0%. Is the upper limit, more preferably less than 10.0%, and still more preferably 9.5%.
As the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

The Yb ₂ O ₃ component is an optional component that can increase the refractive index of the glass and reduce the dispersion when it exceeds 0%.
On the other hand, since the material cost of glass is reduced by making the content of the Yb ₂ O ₃ component 20.0% or less, a cheaper optical glass can be produced. This also increases the devitrification resistance of the glass. Therefore, the content of the Yb ₂ O ₃ component is preferably 20.0%, more preferably 10.0%, and still more preferably 5.0%.
As the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

Sum (mass sum) of contents of Ln ₂ O ₃ components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is 30.0% or more and 75.0% or less Is preferred.
In particular, the dispersion of the glass can be reduced by setting this sum to 30.0% or more. Therefore, the mass sum of the Ln ₂ O ₃ component is preferably 30.0%, more preferably 35.0%, more preferably 40.0%, still more preferably 45.0%, and even more preferably 48.0%. More preferably, the lower limit is 54.0%.
On the other hand, by setting the sum to 75.0% or less, the liquidus temperature of the glass is lowered, so that the devitrification resistance can be improved. Therefore, the mass sum of _Ln 2 _{O 3} component is preferably 75.0%, more preferably 70.0, more preferably 68.0%, more preferably 65.0%, more preferably 60.0% Is the upper limit.

Particularly in the first and second optical glasses, the ratio of the sum of the contents of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component to the sum of the contents of the La ₂ O ₃ component and the Y ₂ O ₃ component (mass ratio). ) Is preferably 0.50 or less. Thereby, since the use of expensive Gd ₂ O ₃ component and Yb ₂ O ₃ component is reduced while maintaining a high Abbe number and high transmittance, the material cost of glass can be suppressed. Therefore, the mass ratio (Gd ₂ O ₃ + Yb ₂ O ₃ ) / (La ₂ O ₃ + Y ₂ O ₃ ) is preferably 0.50, more preferably 0.30, still more preferably 0.22, and even more preferably. The upper limit is 0.20, more preferably 0.19.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index of the glass, increase the devitrification resistance, and increase the viscosity of the molten glass when it contains more than 0%.
On the other hand, by reducing the expensive Ta ₂ O ₅ component to 15.0% or less, the material cost of the glass is reduced, so that a cheaper optical glass can be produced. Moreover, since the melting temperature of a raw material becomes low by this and the energy required for melting of a raw material is reduced, the manufacturing cost of optical glass can also be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably 15.0% or less, more preferably less than 15.0%, even more preferably 13.0% or less, still more preferably less than 13.0%, still more preferably 8.0% or less, more preferably less than 7.0%. In particular, from the viewpoint of producing a cheaper optical glass, the content of the Ta ₂ O ₅ component is preferably 5.0% or less, more preferably less than 5.0%, still more preferably 4.0% or less, Preferably, it is less than 3.0%, more preferably less than 2.0%, more preferably less than 1.0%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

In particular, in the third optical glass, it is preferable to make the B ₂ O ₃ component 30.0% or less while the content of the Ta ₂ O ₅ component is less than 15.0% as described above. Thereby, while increasing the refractive index, the expensive Ta ₂ O ₅ component and the Gd ₂ O ₃ component are reduced, while the B ₂ O ₃ component that lowers the refractive index is reduced, thereby reducing the Ta ₂ O ₅ component. and suppressing a decrease in the refractive index due to the reduction of _Gd 2 _{O 3} component. Therefore, a cheaper optical glass can be obtained while having a desired high refractive index. More preferably, the content of the Ta ₂ O ₅ component is less than 3.0%, the content of the Gd ₂ O ₃ component is less than 10.0%, and the B ₂ O ₃ component is 16.4% or less. Also good.

Particularly, in the third optical glass, it is preferable that the La ₂ O ₃ component is contained at 10.0% or more while the content of the Ta ₂ O ₅ component is less than 15.0% as described above. As a result, while the refractive index is increased, the expensive Ta ₂ O ₅ component is reduced. On the other hand, a La ₂ O ₃ component that is relatively inexpensive among components that increase the refractive index and can maintain a high Abbe number is predetermined. Included. Therefore, it is possible to obtain an optical glass with a low material cost while having a high refractive index and Abbe number. More preferably, the content of the Ta ₂ O ₅ component may be less than 5.0% and the La ₂ O ₃ component may be contained at 40.0% or more.

In particular, in the second and third optical glasses, while the content of the Ta ₂ O ₅ component is 15.0% or less as described above, the sum of the contents of the Ln ₂ O ₃ component is 35.0%. It is preferable to make it above. Thereby, since the Ta ₂ O ₅ component more expensive than the rare earth element is reduced while achieving high refractive index and low dispersion of the optical glass, the material cost of the glass can be suppressed. Further, while the Ta ₂ O ₅ component that lowers the Abbe number is reduced, the desired high Abbe number can be easily obtained by containing a predetermined amount or more of the Ln ₂ O ₃ component that increases the Abbe number. More preferably, the Ta ₂ O ₅ component may be 15.0% or less, and the sum of the contents of the Ln ₂ O ₃ component may be 30.0% or more. More preferably, the content of the Ta ₂ O ₅ component may be less than 5.0%, and the sum of the contents of the Ln ₂ O ₃ component may be 40.0% or more. More preferably, the content of the Ta ₂ O ₅ component may be 4.0% or less, and the sum of the contents of the Ln ₂ O ₃ component may be 40.0% or more.

In the optical glass of the present invention, the sum (mass sum) of the contents of the Gd ₂ O ₃ component, the Yb ₂ O ₃ component, and the Ta ₂ O ₅ component is preferably 30.0% or less. Thereby, since content of these expensive components is reduced, the material cost of glass can be held down. Accordingly, the mass sum (Gd ₂ O ₃ + Yb ₂ O ₃ + Ta ₂ O ₅ ) is preferably 30.0%, more preferably 20.0%, still more preferably 15.0%, and even more preferably 13.0%. More preferably, the upper limit is 10.0%.

The WO ₃ component is an optional component that can increase the refractive index and increase the devitrification resistance of the glass while reducing the coloring of the glass due to other high refractive index components when it contains more than 0%. Further, WO ₃ components, it is also a component can be lowered glass transition temperature. Therefore, the content of the WO ₃ component is preferably more than 0%, more preferably 0.1%, still more preferably 0.5%, and even more preferably 0.6%.
On the other hand, by setting the content of the WO ₃ component to 25.0% or less, coloring of the glass due to the WO ₃ component can be reduced and the visible light transmittance can be increased. Therefore, the upper limit of the content of the WO ₃ component is preferably 25.0%, more preferably 20.0%, still more preferably 15.0%, still more preferably 10.0%, and even more preferably 7.0%. And
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

Nb ₂ O ₅ component, when ultra containing 0%, increased the refractive index of the glass, and is an optional component that enhances devitrification resistance. Therefore, the content of the Nb ₂ O ₅ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 1.5%, still more preferably more than 2.0%, still more preferably 4. It may be over 0%.
On the other hand, by reducing the content of the Nb ₂ O ₅ component to 20.0% or less, it is possible to reduce the devitrification resistance of the glass due to the excessive content of the Nb ₂ O ₅ component and the transmittance of visible light. Can be suppressed. Therefore, the content of the Nb ₂ O ₅ component is preferably 20.0%, more preferably 15.0%, still more preferably 13.0%, and still more preferably 10.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The TiO ₂ component is an optional component that can increase the refractive index of the glass, adjust the Abbe number to a low level, and increase the resistance to devitrification when it contains more than 0%. Therefore, particularly in the first and second optical glasses, the content of the TiO ₂ component is preferably more than 0%, more preferably 0.5%, and even more preferably 1.0%.
On the other hand, by setting the content of TiO ₂ to 30.0% or less, the coloring of the glass is reduced to increase the visible light transmittance, and the glass Abbe number can be prevented from being lowered more than necessary. Further, devitrification due to excessive inclusion of the TiO ₂ component can be suppressed. Therefore, the upper limit of the content of the TiO ₂ component is preferably 30.0%, more preferably 28.0%, and still more preferably 25.0%. In particular, in the first optical glass, the content of the TiO ₂ component is preferably 20.0%, more preferably 18.0%, still more preferably 15.0%, and even more preferably 10.0%. It may be less. In the third optical glass, the content of the TiO ₂ component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably 3.0%. Also good.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

In particular, in the first and second optical glasses, the sum (mass sum) of the contents of the Nb ₂ O ₅ component and the WO ₃ component is preferably 1.0% or more and 30.0% or less.
In particular, by making this sum 1.0% or more, the refractive index of the glass can be increased and coloring can be reduced even if the Ta ₂ O ₅ component and rare earth elements are reduced in order to reduce the material cost of the glass. And devitrification resistance can be improved. Accordingly, the mass sum (Nb ₂ O ₅ + WO ₃ ) is preferably 1.0% as a lower limit, more preferably more than 2.0%, still more preferably more than 4.0%, and still more preferably more than 5.7%. More preferably, it is more than 7.0%, more preferably more than 8.0%.
On the other hand, by making this sum 30.0% or less, coloring caused by excessive inclusion of these components can be reduced, and devitrification resistance can be improved. Therefore, the upper limit of the mass sum (Nb ₂ O ₅ + WO ₃ ) is preferably 30.0%, more preferably 25.0%, and still more preferably 20.0%.

In particular, in the third optical glass, the sum (mass sum) of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 30.0% or less. Thereby, since the fall of Abbe number is suppressed, it can be easy to obtain a desired Abbe number. Further, coloring due to excessive inclusion of these components can be reduced, and devitrification resistance can be enhanced. Accordingly, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 30.0%, more preferably 25.0%, even more preferably 19.0%, still more preferably 16.0%, and even more preferably. The upper limit is 14.0%.
On the other hand, this sum may be 1.0% or more. Accordingly, even when reducing the Ta ₂ O ₅ component or the like in order to reduce the material cost of the glass, an elevated refractive index of the glass, and enhance resistance to devitrification. Therefore, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 1.0% as a lower limit, more preferably more than 2.0%, and even more preferably more than 4.0%.

In particular, in the first optical glass, the content of the Ta ₂ O ₅ component is reduced to 15.0% or less while reducing the B ₂ O ₃ component to 30.0% or less as described above, and Nb ₂ O ₅ The sum of the contents of the components and the WO ₃ components is preferably 1.0% or more. Thus, while the B ₂ O ₃ component to lower the refractive index is reduced, Nb ₂ O ₅ component, and WO ₃ components to increase the refractive index of that contained more than a predetermined refractive index of the glass is increased. At the same time, among the components that increase the refractive index and resistance to devitrification, the expensive Ta ₂ O ₅ component is reduced, while the cheaper Nb ₂ O ₅ component and the WO ₃ component are contained, so An optical glass with high devitrification is obtained. Therefore, the material cost of optical glass having a high refractive index and high devitrification resistance can be suppressed. More preferably, the B ₂ O ₃ component is 16.4% or less, the content of the Ta ₂ O ₅ component is 5.0% or less, and the sum of the contents of the Nb ₂ O ₅ component and the WO ₃ component is 7 It may be 0% or more.

The SiO ₂ component is an optional component that, when contained over 0%, can increase the viscosity of the molten glass, reduce the coloration of the glass, and increase the devitrification resistance. Therefore, the content of the SiO ₂ component is preferably more than 0%, more preferably 1.0%, still more preferably 2.0%, and even more preferably 3.0%. In particular, in the third optical glass, the content of the SiO ₂ component may be 5.0% or more, more preferably more than 6.0%.
On the other hand, when the content of the SiO ₂ component is 30.0% or less, an increase in the glass transition point can be suppressed and a decrease in the refractive index can be suppressed. Accordingly, the upper limit of the content of the SiO ₂ component is preferably 30.0%, more preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%. In particular, in the first and second optical glasses, the upper limit may be 8.0%.
As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

Here, the sum (mass sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 1.0% or more and 30.0% or less.
In particular, by making this sum 1.0% or more, it is possible to suppress a decrease in devitrification resistance due to the lack of the B ₂ O ₃ component or the SiO ₂ component. Accordingly, the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 1.0%, more preferably 5.0%, still more preferably 10.0%, still more preferably 15.0%, and even more preferably 18. 0% is the lower limit.
On the other hand, by making this sum 30.0% or less, a decrease in the refractive index due to excessive inclusion of these components can be suppressed, so that a desired high refractive index can be easily obtained. Therefore, the mass sum (B ₂ O ₃ + SiO ₂ ) is preferably 30.0%, more preferably 27.0%, still more preferably 25.0%, still more preferably 24.0%, and even more preferably 21.%. The upper limit is 0%.

In particular, in the first and second optical glasses, the ratio (mass ratio) of the sum of the contents of the Nb ₂ O ₅ component and the WO ₃ component to the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 0. .15 or more and 2.00 or less is preferable.
In particular, by setting this ratio to 0.15 or more, the refractive index can be increased while maintaining high devitrification resistance. Therefore, the mass ratio (Nb ₂ O ₅ + WO ₃ ) / (B ₂ O ₃ + SiO ₂ ) is preferably 0.15, more preferably 0.25, still more preferably 0.30, and even more preferably 0.35. More preferably, the lower limit is 0.40, more preferably 0.43.
On the other hand, by the ratio 2.00, suppressing excessive content or _Nb 2 _{O 5} component and WO _{3 components,} a reduction in the devitrification resistance due to absence of the B 2 _{O 3} component and the SiO ₂ component It is done. Therefore, the mass ratio (Nb ₂ O ₅ + WO ₃ ) / (B ₂ O ₃ + SiO ₂ ) is preferably 2.00, more preferably 1.50, and still more preferably 1.20.

The MgO component, CaO component, SrO component, and BaO component are optional components that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when the content exceeds 0%.
On the other hand, the content of each of the MgO component, the CaO component and the SrO component is made 20.0% or less and / or the content of the BaO component is made 25.0% or less. Reduction of refractive index and devitrification resistance due to excessive inclusion can be suppressed. Therefore, the content of each of the MgO component, CaO component and SrO component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably 3.0%. To do. Further, the content of the BaO component is preferably 25.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 8.0%.
MgO component, CaO component, SrO component and BaO component are MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF _{2 and the} like as raw materials. Can be used.

The total content (mass sum) of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 25.0% or less. Thereby, the fall of the refractive index of glass and the fall of devitrification resistance by containing excessive RO component can be suppressed. Accordingly, the upper limit of the mass sum of the RO component is preferably 25.0%, more preferably 15.0%, still more preferably 10.0%, and still more preferably 5.0%.

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 difficult to lower the refractive index of the glass and the devitrification resistance can be improved. In addition, the viscosity of the molten glass can be increased thereby, the striae of the glass can be reduced, and the chemical durability of the glass can be increased. Therefore, the content of the Li ₂ O component is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, still more preferably 3.0% or less, and even more preferably 1 0.0% or less, more preferably less than 1.0%, more preferably 0.3% or less, and still more preferably less than 0.3%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , Li ₂ CO ₃ or the like can be used as a raw material.

Na ₂ O component, K ₂ O component, and Cs ₂ O component are optional components that can improve the meltability of glass, increase the devitrification resistance of glass, and lower the glass transition point when contained in excess of 0%. It is. Here, by making each content of the Na ₂ O component, the K ₂ O component and the Cs ₂ O component 10.0% or less, it is difficult to lower the refractive index of the glass, and the devitrification resistance is improved. Enhanced. Therefore, the content of each of the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component is preferably 10.0%, more preferably 8.0%, still more preferably 5.0%, and even more preferably 3%. 0.0% is the upper limit.
Na ₂ O component, _{K 2} O component and Cs ₂ O component, NaNO ₃ as a raw _{material, NaF, Na 2 SiF 6,} K 2 CO 3, KNO 3, KF, KHF 2, K 2 SiF 6, Cs 2 CO 3 , CsNO ₃ or the like can be used.

In particular, in the third optical glass, the content of the Ta ₂ O ₅ component is less than 15.0% as described above, but the B ₂ O ₃ component is reduced to 30.0% or less, and the Li ₂ O component The content of is preferably 10.0% or less. As a result, while the refractive index is increased, the expensive Ta ₂ O ₅ component is reduced, while the B ₂ O ₃ component and the Li ₂ O component that lower the refractive index are reduced, thereby reducing the Ta ₂ O ₅ component. A decrease in refractive index due to the reduction can be suppressed. Therefore, an optical glass having a high refractive index and a reduced material cost can be obtained. More preferably, the content of the Ta ₂ O ₅ component is less than 5.0%, the B ₂ O ₃ component is reduced to 18.0% or less, and the content of the Li ₂ O component is less than 1.0%. May be.

The total amount of Rn ₂ O components (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is preferably 15.0% or less. Thereby, the fall of the refractive index of glass can be suppressed and devitrification resistance can be improved. Therefore, the upper limit of the mass sum of the Rn ₂ O component is preferably 15.0%, more preferably 10.0%, and still more preferably 5.0%.

P ₂ O ₅ component, when ultra containing 0%, which is an optional component that enhances devitrification resistance of the glass. In particular, by making the content of the P ₂ O ₅ component 10.0% or less, it is possible to suppress a decrease in chemical durability, particularly water resistance, of the glass. Therefore, the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like can be used as a raw material.

The GeO ₂ component is an optional component that can increase the refractive index of the glass and improve the devitrification resistance when it contains more than 0%. However, GeO ₂ has a high raw material price, by material cost increases and the amount is large, the effect of cost reduction by reducing the _Gd 2 O ₃ component and the Ta ₂ O ₅ component or the like is diminished. Accordingly, the content of the GeO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 1.0%, and most preferably not contained.
As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

When the ZrO ₂ component is contained in an amount of more than 0%, it can contribute to a higher refractive index and a lower dispersion of the glass, and the devitrification resistance of the glass can be improved. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably 1.0%, and even more preferably 3.0%.
On the other hand, by making the ZrO ₂ component 15.0% or less, it is possible to suppress a decrease in the devitrification resistance of the glass due to the excessive inclusion of the ZrO ₂ component. Therefore, the upper limit of the content of the ZrO ₂ component is preferably 15.0%, more preferably 10.0%, and still more preferably 8.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The ZnO component is an optional component that can lower the glass transition point and increase chemical durability when it is contained in excess of 0%. Therefore, particularly in the third optical glass, the content of the ZnO component is preferably more than 0%, more preferably 1.0%, and even more preferably 3.0%.
On the other hand, by setting the content of the ZnO component to 25.0% or less, a decrease in the refractive index of glass and a decrease in devitrification resistance can be suppressed. Moreover, since the viscosity of molten glass is raised by this, generation | occurrence | production of the striae to glass can be reduced. Therefore, the content of the ZnO component is preferably 25.0%, more preferably 22.0%, and further preferably 20.0%. In particular, in the first and second optical glasses, the content of the ZnO component is preferably 15.0% or less, more preferably 10.0% or less, still more preferably 5.0% or less, and even more preferably 5. It may be less than 0%, more preferably 1.1% or less.
As the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

In particular, in the third optical glass, it is preferable to reduce the ZnO component to 25.0% or less while the content of the Ta ₂ O ₅ component is less than 15.0% as described above. Thereby, while increasing the viscosity and devitrification resistance of the molten glass, the expensive Ta ₂ O ₅ component is reduced, while the ZnO component lowering the viscosity of the molten glass is reduced. Therefore, the material cost can be suppressed while the striae is reduced, and a glass excellent in mass productivity can be manufactured in terms of high devitrification resistance. More preferably, the content of the Ta ₂ O ₅ component may be less than 5.0% and the ZnO component may be 25.0% or less.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can increase the chemical durability of the glass and increase the devitrification resistance of the glass when contained in excess of 0%.
On the other hand, by making each content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component 10.0% or less, a decrease in the devitrification resistance of the glass due to the excessive content thereof can be suppressed. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
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.

A Bi ₂ O ₃ component is an optional component that can increase the refractive index and lower the glass transition point when it exceeds 0%.
On the other hand, by the content of Bi ₂ O ₃ component to 10.0% or less, enhanced resistance to devitrification of the glass, and it is enhanced visible light transmittance to reduce the coloration of the glass. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.
As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component that can increase the refractive index and lower the glass transition point when it is contained in excess of 0%.
However, TeO ₂ has a problem that it can be alloyed with platinum when a glass raw material is melted in a crucible made of platinum or a melting tank in which a portion in contact with molten glass is formed of platinum. Accordingly, the content of the TeO ₂ component is preferably 20.0%, more preferably 10.0%, still more preferably 5.0%, and even more preferably not contained.
TeO ₂ component can use TeO ₂ or the like as a raw material.

When the SnO ₂ component is contained in an amount of more than 0%, the SnO ₂ component is an optional component that can be refined by reducing the oxidation of the molten glass and can increase the visible light transmittance of the glass.
On the other hand, by setting the content of the SnO ₂ component to 1.0% or less, it is possible to reduce the coloration of the glass due to the reduction of the molten glass and the glass devitrification. Further, since the alloying of the SnO ₂ component and the melting equipment (especially a noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 1.0%, more preferably 0.7%, and still more preferably 0.5%.
For the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like can be used as a raw material.

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

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

<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 characteristics of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is independent of each other. Or, even when it is contained in a small amount in combination, the glass is colored and has the property of causing absorption at a specific wavelength in the visible range. .

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

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

The glass composition of the present invention cannot be expressed directly in the description of mol% because the composition is expressed by mass% with respect to the total mass of the glass of oxide conversion composition, but various properties required in the present invention. The composition expressed by mol% of each component present in the glass composition satisfying the above conditions generally takes the following values in terms of oxide conversion.
B ₂ O ₃ component 2.0 to 55.0 mol%, and La ₂ O ₃ component 5.0 to 30.0 mol%,
Y ₂ O ₃ component 0-20.0 mol%,
Gd ₂ O ₃ component 0-20.0 mol%,
Yb ₂ O ₃ component 0-10.0 mol%,
Ta ₂ O ₅ component 0 to 5.0 mol%,
WO ₃ component 0-20.0 mol%,
Nb ₂ O ₅ component 0 to 15.0 mol%,
TiO ₂ component 0-50.0 mol%,
SiO ₂ component 0-60.0 mol%,
MgO component 0-50.0 mol%,
CaO component 0-40.0 mol%,
SrO component 0-30.0 mol%,
BaO component 0-35.0 mol%,
Li ₂ O component 0-30.0 mol%,
Na ₂ O component 0-25.0 mol%,
K ₂ O component 0-20.0 mol%,
Cs ₂ O component 0-10.0 mol%,
P ₂ O ₅ component 0 to 15.0 mol%,
GeO ₂ component 0-10.0 mol%,
ZrO ₂ component from 0 to 20.0 mol%,
ZnO component 0-60.0 mol%,
Al ₂ O ₃ component 0-20.0 mol%,
Ga ₂ O ₃ component 0-5.0 mol%,
Bi ₂ O ₃ component 0-5.0 mol%,
TeO ₂ component 0-20.0 mol%,
SnO ₂ component 0 to 0.3 mol%, or Sb ₂ O ₃ component 0 to 0.5 mol%

In particular, in the first optical glass, the composition expressed by mol% of the following components may take the following value as an oxide conversion composition.
TiO ₂ component 0-40.0 mol%,
SiO ₂ component 0 to 50.0 mol%, or ZnO component 0 to 50.0 mol%,

Further, in the second optical glass, the composition expressed by mol% of the following components may take the following value as an oxide conversion composition.
Gd ₂ O ₃ component 0-10.0 mol%,
SiO ₂ component 0 to 50.0 mol%, or ZnO component 0 to 50.0 mol%,

Further, in the third optical glass, the composition expressed by mol% of the following components may take the following value as an oxide conversion composition.
TiO ₂ component 0-30.0 mol%,
WO ₃ component 0-15.0 mol%,
MgO component 0-25.0 mol%,
CaO component 0-20.0 mol%, or SrO component 0-15.0 mol%,

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

[Physical properties]
The optical glass of the present invention preferably has a high refractive index and a high Abbe number (low dispersion). In particular, the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75, more preferably 1.80, even more preferably 1.83, and even more preferably 1.85. The upper limit of this refractive index is preferably 2.20, more preferably 2.15, and even more preferably 2.10.
Further, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 23, more preferably 24, still more preferably 25, and even more preferably 27. In particular, the Abbe number (ν _d ) of the first optical glass is preferably 28, more preferably 30, still more preferably 31, and even more preferably 32. Further, the Abbe number (ν _d ) of the third optical glass is preferably 35, more preferably 37, and still more preferably 39.
On the other hand, the upper limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 50, more preferably 47, and more preferably 45. In particular, the Abbe number (ν _d ) of the first and second optical glasses is preferably 40, more preferably 39.5, and even more preferably less than 39.
By having such a high refractive index, a large amount of light can be obtained even if the optical element is thinned. In addition, by having such low dispersion, even with a single lens, focus shift (chromatic aberration) due to the wavelength of light is reduced. In addition, by having such low dispersion, for example, when combined with an optical element having high dispersion (low Abbe number), high imaging characteristics and the like can be achieved.
Therefore, the optical glass of the present invention is useful in optical design, and the optical system can be miniaturized and the degree of freedom in optical design can be expanded while achieving particularly high imaging characteristics.

The optical glass of the present invention preferably has high devitrification resistance, more specifically, a low liquidus temperature. That is, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1300 ° C, more preferably 1290 ° C, and still more preferably 1280 ° C. As a result, even if the molten glass flows out at a lower temperature, crystallization of the produced glass is reduced, and thus devitrification when the glass is formed from a molten state can be reduced, and an optical element using glass The influence on the optical characteristics can be reduced. Moreover, since glass can be shape | molded even if the melting temperature of glass is lowered | hung, the manufacturing cost of glass can be reduced by suppressing the energy consumed at the time of shaping | molding glass. 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 preferably 500 ° C, more preferably 600 ° C, and even more preferably 700 ° C. Also good. In this specification, “liquid phase temperature” refers to a 30 ml cullet-shaped glass sample placed in a platinum crucible in a 50 ml capacity platinum crucible, completely melted at 1350 ° C., and cooled to a predetermined temperature. The glass surface and the presence or absence of crystals in the glass are observed immediately after taking out of the furnace and cooling, and indicates the lowest temperature at which no crystals are observed. The predetermined temperature when the temperature is lowered is a temperature in increments of 10 ° C. up to 1300 ° C.

It is preferable that the optical glass of the present invention has high visible light transmittance, in particular, high transmittance of light on the short wavelength side of visible light, and thereby less coloring.
In particular, when the optical glass of the present invention is represented by the transmittance of the glass, the wavelength (λ ₇₀ ) showing a spectral transmittance of 70% in a sample having a thickness of 10 mm is preferably 550 nm, more preferably 520 nm, still more preferably 500 nm, More preferably, the upper limit is 480 nm. In particular, in the third optical glass, the wavelength (λ ₇₀ ) exhibiting a spectral transmittance of 70% in a sample having a thickness of 10 mm is more preferably 450 nm, and even more preferably 400 nm.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) having a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 440 nm, more preferably 420 nm, still more preferably 400 nm, further preferably 380 nm. And In particular, in the third optical glass, the shortest wavelength (λ ₅ ) exhibiting a spectral transmittance of 5% in a sample having a thickness of 10 mm may have an upper limit of 360 nm.
As a result, the absorption edge of the glass is in the vicinity of the ultraviolet region, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element that transmits light such as a lens.

The optical glass of the present invention preferably has a low partial dispersion ratio (θg, F). More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is (−2.50 × 10 ⁻³ × ν _d +0.6571) ≦ with respect to the Abbe number (ν _d ) ≦ It is preferable to satisfy the relationship (θg, F) ≦ (−2.50 × 10 ⁻³ × ν _d +0.6971). Thereby, since an optical glass having a small partial dispersion ratio (θg, F) is obtained, the optical glass is useful for reducing chromatic aberration of an optical element.
Therefore, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably (−2.50 × 10 ⁻³ × ν _d +0.6571), more preferably (−2.50 × 10 ⁻³ ×). (ν _d +0.6591), more preferably (−2.50 × 10 ⁻³ × ν _d +0.6611) is set as the lower limit.
On the other hand, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably (−2.50 × 10 ⁻³ × ν _d +0.6971), more preferably (−2.50 × 10 ^−3). × ν _d +0.6921), more preferably (−2.50 × 10 ⁻³ × ν _d +0.6871).

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 [g / cm ³ ] or less. Thereby, since the mass of an optical element and an optical apparatus using the same is reduced, it can contribute to the weight reduction of an optical apparatus. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.50, more preferably 5.40, still more preferably 5.30, and still more preferably 5.10. The specific gravity of the optical glass of the present invention is generally about 3.00 or more, more specifically 3.50 or more, and more specifically 4.00 or more in many cases.
The specific gravity of the optical glass of the present invention is measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 “Method for Measuring Specific Gravity of Optical Glass”.

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

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

Compositions of Examples (No. 1 to No. 398) and Comparative Examples (No. A to No. C), and refractive indexes (n _d ), Abbe numbers (ν _d ), partial dispersion ratios of these glasses ( Tables 1 to 56 show the results of θg, F), liquid phase temperature, wavelengths (λ ₅ and λ ₇₀ ) at which the spectral transmittance is 5% and 70%, and specific gravity. Of these, Examples (No. 1 to No. 132) are examples of the first optical glass of the present invention. Examples (No. 133 to No. 282) and comparative examples (No. A, No. B) are examples and comparative examples of the second optical glass of the present invention. Examples (No. 283 to No. 398) and comparative examples (No. C) are examples and comparative examples of the third optical glass of the present invention.
The following examples are merely for illustrative purposes, and are not limited to these examples.

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

Here, the refractive index, Abbe number, and partial dispersion ratio (θg, F) of the glasses of the examples and comparative examples were measured based on Japan Optical Glass Industry Association Standard JOGIS01-2003. Then, with respect to the obtained Abbe number and partial dispersion ratio, the intercept b when the slope a is 0.0025 in the relational expression (θg, F) = − a × ν _d + b was obtained. Here, the refractive index, Abbe number, and partial dispersion ratio were determined by measuring the glass obtained at a slow cooling rate of -25 ° C / hr.

Moreover, 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 ₇₀ (transmittance). Wavelength at 70%).

The liquid phase temperature of the glass of the examples and comparative examples is as follows: a 30 cc cullet-shaped glass sample is placed in a platinum crucible in a platinum crucible having a capacity of 50 ml and completely melted at 1350 ° C., 1300 ° C. to 1160 ° C. The temperature is lowered to any temperature set in increments of 10 ° C. and held for 12 hours. After taking out of the furnace and cooling, the glass surface and the presence or absence of crystals in the glass are observed immediately, and the lowest crystal is not observed. The temperature was determined.

The specific gravity of the glasses of the examples and comparative examples was measured based on the Japan Optical Glass Industry Association Standard JOGIS05-1975 “Method for Measuring Specific Gravity of Optical Glass”.

The optical glasses of the examples of the present invention all had a liquidus temperature of 1300 ° C. or lower, more specifically 1220 ° C. or lower, and were within a desired range. On the other hand, since the comparative example (No. A) was highly devitrified and did not vitrify, the liquidus temperature could not be measured. Moreover, the liquidus temperature exceeded 1300 degreeC in the comparative example (No. B). For this reason, it became clear that the optical glass of the Example of this invention has a low liquidus temperature and high devitrification resistance compared with the glass of a comparative example (No.A, No.B).

In addition, in the optical glasses of the examples of the present invention, each of λ ₇₀ (wavelength at a transmittance of 70%) was 550 nm or less, more specifically, 513 nm or less. In particular, λ ₇₀ of the first optical glass was 505 nm or less. In addition, λ ₇₀ of the third optical glass was 391 nm or less.
The optical glasses of the examples of the present invention all had λ ₅ (wavelength at a transmittance of 5%) of 440 nm or less, more specifically 396 nm or less. In particular, λ ₅ of the first optical glass was 379 nm or less. Further, λ ₅ of the third optical glass was 341 nm or less.

The optical glasses of the examples of the present invention all have a refractive index (n _d ) of 1.75 or more, more specifically 1.85 or more, and this refractive index is 2.20 or less, more specifically. Was 2.06 or less, and was within the desired range.
In particular, the refractive index (n _d ) of the first optical glass was in the range of 1.87 to 2.01. The refractive index (n _d ) of the second optical glass was in the range of 1.87 to 2.06. The refractive index (n _d ) of the third optical glass was in the range of 1.85 to 1.95.

The optical glasses of the examples of the present invention all have an Abbe number (ν _d ) of 23 or more, more specifically 24 or more, and this Abbe number is 50 or less, more specifically 42 or less, It was within the desired range.
In particular, the Abbe number (ν _d ) of the first optical glass was in the range of 28 to 39. Further, the Abbe number (ν _d ) of the second optical glass was in the range of 24 to 39. The Abbe number (ν _d ) of the third optical glass was in the range of 35 to 42.

The optical glasses of the examples of the present invention all have a partial dispersion ratio (θg, F) of (−2.50 × 10 ⁻³ × ν _d +0.6571) or more, more specifically (−2.50). × 10 ⁻³ × ν _d +0.6658) or more. On the other hand, the partial dispersion ratio (-2.50 × 10 ⁻³ × ν _d +0.6971) or less of the optical glass of the example of the present invention, more specifically (−2.50 × 10 ⁻³ × ν _d). +0.6785) or less. Therefore, it was found that these partial dispersion ratios (θg, F) are within a desired range.
In particular, the partial dispersion ratio (θg, F) of the first optical glass is (−2.50 × 10 ⁻³ × ν _d +0.6683) or more (−2.50 × 10 ⁻³ × ν _d +0.6750). ) It was within the following range. The Abbe number of the second optical glass ([nu _d) ^{is, (- 2.50 × 10 -3 ×} ν d +0.6658) or _{^{(-2.50 × 10 -3 × ν d}} +0.6785) below It was in the range. The Abbe number of the third optical glass ([nu _d) ^{is, (- 2.50 × 10 -3 ×} ν d +0.6691) or _{^{(-2.50 × 10 -3 × ν d}} +0.6761) below It was in the range.

The optical glasses of the examples of the present invention all had a specific gravity of 5.50 or less, more specifically 5.20 or less. In particular, the specific gravity of the third optical glass was 4.96 or less. Therefore, it became clear that the optical glass of the Example of this invention has small specific gravity.

Therefore, it is clear that the optical glass of the embodiment of the present invention can be manufactured at a low cost while having a refractive index and an Abbe number within a desired range, has high resistance to devitrification, little coloring, and low specific gravity. became.

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 (27)

1. An optical glass containing 1.0 to 30.0% of a B ₂ O ₃ component and 10.0 to 60.0% of a La ₂ O ₃ component by mass%.
2. The optical glass according to claim 1, wherein the content of the Ta ₂ O ₅ component is 15.0% or less by mass.
3. 3. The optical glass according to claim 1, wherein the optical glass has an Abbe number (ν _d ) of 35 or more and the content of the Ta ₂ O ₅ component is less than 15.0%.
4. The optical glass according to any one of claims 1 to 3, wherein the content of the Y ₂ O ₃ component is 30.0% or less in terms of mass%.
5. The optical glass according to any one of claims 1 to 4, wherein the content of the Gd ₂ O ₃ component is 40.0% or less in terms of mass%.
6. The optical glass according to any one of claims 1 to 5, wherein the content of the Gd ₂ O ₃ component is 20.0% or less by mass%.
7. The optical glass according to claim 1, wherein the content of the Yb ₂ O ₃ component is 20.0% or less by mass.
8. 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) is 30.0% or more and 75.0% or less. The optical glass according to any one of the above.
9. The optical glass according to any one of claims 1 to 8, wherein a mass ratio (Gd ₂ O ₃ + Yb ₂ O ₃ ) / (La ₂ O ₃ + Y ₂ O ₃ ) is 0.50 or less.
10. The optical glass according to claim 1, wherein the sum of the contents of the Gd ₂ O ₃ component, the Yb ₂ O ₃ component, and the Ta ₂ O ₅ component is 30.0% or less.
11. TiO ₂ component by mass% 0-30.0%
    Nb ₂ O ₅ component 0-20.0%
    WO ₃ component 0-25.0%
    The optical glass according to any one of claims 1 to 10.
12. The optical glass according to claim 1, wherein the sum of the contents of the Nb ₂ O ₅ component and the WO ₃ component is 1.0% or more and 30.0% or less.
13. The optical glass according to any one of claims 1 to 12, wherein the sum of the contents of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is 30.0% or less.
14. The optical glass according to any one of claims 1 to 13, wherein the content of the SiO ₂ component is 30.0% or less in terms of mass%.
15. The optical glass according to any one of claims 1 to 14, wherein the sum of the contents of the B ₂ O ₃ component and the SiO ₂ component is 1.0% or more and 30.0% or less.
16. The optical glass according to claim 1, wherein a mass ratio (Nb ₂ O ₅ + WO ₃ ) / (B ₂ O ₃ + SiO ₂ ) is 0.15 or more and 2.00 or less.
17. MgO component in mass% 0 to 20.0%
    CaO component 0-20.0%
    SrO component 0-20.0%
    BaO component 0-25.0%
    The optical glass according to any one of claims 1 to 16.
18. The optical glass according to any one of claims 1 to 17, wherein a mass sum of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 25.0% or less.
19. The optical glass according to any one of claims 1 to 18, wherein the content of the Li ₂ O component is 10.0% or less by mass.
20. Na ₂ O component by mass% 0-10.0%
    K ₂ O component 0-10.0%
    Cs ₂ O component 0 to 10.0%
    The optical glass according to claim 1, wherein:
21. 21. The optical component according to claim 1, wherein the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, K, and Cs) has a mass sum of 15.0% or less. Glass.
22. The optical glass according to any one of claims 1 to 21, wherein the content of the ZnO component is 25.0% or less by mass%.
23. Mass% with _P 2 _{O 5} component from 0 to 10.0%
    GeO ₂ component 0 ～ 10.0%
    ZrO ₂ component 0 ～ 15.0%
    ZnO component 0-15.0%
    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 component 0-20.0%
    SnO ₂ component 0-1.0%
    Sb ₂ O ₃ component 0-1.0%
    The optical glass according to any one of claims 1 to 22.
24. The optical glass according to claim 1, which has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 23 or more and 50 or less.
25. The optical glass according to claim 1, which has a liquidus temperature of 1300 ° C. or lower.
26. An optical element having the optical glass according to any one of claims 1 to 25 as a base material.
27. An optical device comprising the optical element according to claim 26.