TW201620847A - Optical glass, preform and optical element - Google Patents

Abstract

The present invention more cheaply provides an optical glass which has a small partial dispersion ratio ([Theta]g, F), with the index of refraction (nd) and the Abbe number (vd) being within a desired range. An optical glass of the present invention contains 10.0-40.0 mass% of SiO2 and 40.0 mass% or less of Nb2O5, and has a total mass (Nb2O5 + TiO2 + ZrO2) of 10.0-60.0 mass%, an index of refraction (nd) between 1.65 and 1.90, an Abbe number (vd) between 25 and 45, and a partial dispersion ratio ([Theta]g, F) of 0.615 or less.

Description

Optical glass, preforms and optical components

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

Optical systems such as digital cameras or camcorders contain more or less blurs called aberrations. This aberration is divided into monochromatic aberration and chromatic aberration, and in particular, chromatic aberration is strongly dependent on the material properties of the lens used in the optical system.

Generally, chromatic aberration is corrected by combining a low-dispersion convex lens with a highly-dispersed concave lens, but with this combination, only the aberration between the red region and the green region can be corrected, and the aberration of the blue region remains. The aberration of the blue region that cannot be completely removed is referred to as a secondary spectrum. In order to correct the secondary spectrum, the optical design of the movement of the g-ray (435.835 nm) added to the blue region must be performed. At this time, the partial dispersion ratio (θg, F) was used as an index of the optical characteristics of the optical design. In an optical system in which the above-described low-dispersion lens is combined with a highly-dispersed lens, an optical material having a large partial dispersion ratio (θg, F) is used for the lens on the low dispersion side, and a partial dispersion ratio is used for the lens on the high dispersion side ( Θg, F) a smaller optical material whereby the secondary spectrum is well corrected.

The partial dispersion ratio (θg, F) is represented by the following formula (1).

Θg,F=(n _g -n _F )/(n _F -n _C )‧‧‧‧‧‧(1)

There is a substantially linear relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of the optical glass in the partial dispersion of the short-wavelength region. The straight line indicating the relationship is obtained by taking the partial dispersion ratio (θg, F) on the vertical axis and the Abbe number (ν _d ) on the horizontal axis to the partial dispersion ratio of the NSL7 and PBM2 and the Abbe number. The line connecting the two points of the drawing is represented by a straight line (refer to Fig. 1). The ordinary glass that becomes the basis for the regular line varies according to each optical glass manufacturer, and each company is defined by roughly the same slope and intercept. (NSL7 and PBM2 are optical glasses manufactured by OHARA Co., Ltd., the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) of NSL7 is 60.5. The dispersion ratio (θg, F) was 0.5436).

Here, as the glass having an Abbe number (νd) of 25 or more and 45 or less, for example, optical glasses as disclosed in Patent Documents 1 to 3 are known.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2011-037660

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2012-006788

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2012-229135

However, the glass-based portions disclosed in Patent Documents 1 to 3 are relatively large in dispersion, and are insufficient for use as a lens for correcting the above-described secondary spectrum.

Further, in order to reduce the material cost of the optical glass, it is desirable that the raw material cost of each component constituting the optical glass be as low as possible. However, it is difficult to consider that the glass described in Patent Documents 1 to 3 is sufficient for satisfying such requirements.

The present invention has been made in view of the above problems, and an object thereof is to obtain a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range at a lower cost, and a partial dispersion ratio (θg, F) is small. Optical glass.

In order to solve the above problems, the inventors of the present invention have tried their best to carry out experimental research. As a result, it has been found that the content and mass of the Nb ₂ O ₅ component and (Nb ₂ O ₅ +TiO ₂ +ZrO ₂ ) are specific to the SiO ₂ component. The glass in the range, even if the material cost is lowered, can obtain a glass having a refractive index or Abbe number (higher dispersion) in a desired range and a lower partial dispersion ratio, thereby completing the present invention.

In particular, the invention provides the following.

(1) An optical glass containing, by mass%, 10.0 to 40.0% of SiO ₂ component and 40.0% or less of Nb ₂ O ₅ component, and mass (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) of 10.0 to 60.0 % has a refractive index (n _d ) of 1.65 or more and 1.90 or less, an Abbe number (ν _d ) of 25 or more and 45 or less, and a partial dispersion ratio (θg, F) of 0.615 or less.

(2) The optical glass according to (1), wherein the TiO ₂ component is 0 to 20.0% by mass%, the ZrO ₂ component is 0 to 20.0%, the Li ₂ O component is 0 to 15.0%, and the Na ₂ O component is 0. 15.0%.

(3) The optical glass according to (1) or (2), wherein the La ₂ O ₃ component is 0 to 20.0% by mass%, the Gd ₂ O ₃ component is 0 to 10.0%, and the Y ₂ O ₃ component is 0. 20.0% Yb ₂ O ₃ component is 0~10.0% MgO component is 0~10.0% CaO component is 0~15.0% SrO component is 0~10.0% BaO component is 0~60.0% ZnO component is 0~15.0% K ₂ O The composition is 0~10.0% P ₂ O ₅ is 0~10.0% B ₂ O ₃ is 0~15.0% GeO ₂ is 0~10.0% Ta ₂ O ₅ is 0~10.0% WO ₃ is 0~ 10.0% Al ₂ O ₃ component is 0~10.0% Ga ₂ O ₃ component is 0~10.0% Bi ₂ O ₃ component is 0~10.0% TeO ₂ component is 0~10.0% SnO ₂ component is 0~5.0% Sb ₂ The O ₃ component is 0 to 1.0%.

The optical glass according to any one of (1) to (3), wherein the mass ratio (TiO ₂ + ZrO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) is 0.10 or more.

(5) The optical glass according to any one of (1) to (4) wherein the mass ratio (ZrO ₂ ) / (Nb ₂ O ₅ + ZrO ₂ ) is 0.10 or more.

A group according to any one of (6) (1) to (5) of optical glass, wherein Ln ₂ O ₃ component (wherein, Ln is selected from the group consisting of Y, La, Gd, Yb consisting of one or more kinds of the The quality sum is 20.0% or less.

The optical glass according to any one of (1) to (6), wherein the mass ratio (ZrO ₂ ) / (Nb ₂ O ₅ + Ln ₂ O ₃ ) is 0.10 or more and 3.00 or less.

(8) The optical glass according to any one of (1) to (7), wherein the quality of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) The sum is 60.0% or less.

The optical glass according to any one of (1) to (8), wherein the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) And the ratio is 30.0% or less.

The optical glass according to any one of (1) to (9), wherein the spectral transmittance shows that 70% of the wavelength (λ ₇₀ ) is 460 nm or less.

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

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

(13) An optical element obtained by subjecting a preform according to (12) to precise pressurization.

According to the present invention, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range and having a small partial dispersion ratio (θg, F) can be obtained at a lower cost.

Fig. 1 is a view showing a partial dispersion ratio (θg, F) as a vertical axis and an Abbe number (ν _d ) as a normal line indicated by orthogonal coordinates on the horizontal axis.

Fig. 2 is a graph showing the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) in the examples of the present invention.

Fig. 3 is a graph showing the relationship between the refractive index (nd) and the Abbe number (ν _d ) in the embodiment of the present invention.

The optical glass of the present invention contains, by mass%, 10.0 to 40.0% of the SiO ₂ component and 40.0% or less of the Nb ₂ O ₅ component, and the mass and (Nb ₂ O ₅ +TiO ₂ +ZrO ₂ ) are 10.0 to 60.0%. Further, it has a refractive index (n _d ) of 1.65 or more and 1.90 or less, an Abbe number (ν _d ) of 25 or more and 45 or less, and a partial dispersion ratio (θg, F) of 0.615 or less.

In the glass containing the SiO ₂ component and the content and mass of the Nb ₂ O ₅ component and (Nb ₂ O ₅ +TiO ₂ +ZrO ₂ ) in a specific range, even if the use of the Nb ₂ O ₅ component is reduced, etc., The cost of the material can also be obtained with a glass having a refractive index or an Abbe number (higher dispersion) in a desired range and a lower partial dispersion ratio.

Therefore, the refractive index (n _d ) and the Abbe number (ν _d ) can be obtained at a lower cost within a desired range, and the partial dispersion ratio (θg, F) is small, and the chromatic aberration of the optical system is reduced. Useful optical glass.

Further, an optical glass which can contribute to weight reduction of an optical device due to a small specific gravity and a high transmittance to visible light can be preferably used for the purpose of transmitting visible light, and Since the transfer point is low, it is suitable for forming by press forming.

In the following, the embodiment of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be appropriately modified and implemented within the scope of the object of the present invention. In addition, the description of the part to be repeated will be appropriately omitted, but the present invention is not limited.

[Glass composition]

The composition range of each component constituting the optical glass of the present invention is explained below. In the present specification, the content of each component is expressed by mass% based on the total mass of the glass in terms of oxide composition, unless otherwise specified. Here, the "oxide-converting composition" is a case where the oxide, the composite salt, and the metal fluoride which are assumed to be used as the raw material of the glass constituent component of the present invention are equal to being completely decomposed and converted into an oxide at the time of melting. The total mass of the produced oxide was set to 100% by mass, and the composition of each component contained in the glass was described.

<About essential ingredients, optional ingredients>

The SiO ₂ component promotes stable glass formation and reduces the necessity of devitrification (production of crystals) which is an excellent optical glass.

In particular, by setting the content of the SiO ₂ component to 10.0% or more, it is not necessary to greatly increase the partial dispersion ratio, and a glass excellent in devitrification resistance can be obtained. Moreover, by this, devitrification or coloring at the time of reheating can be reduced. Therefore, the content of the SiO ₂ component is preferably 10.0% as the lower limit, more preferably 12.0% as the lower limit, still more preferably 15.0% as the lower limit, and further preferably 18.5% as the lower limit.

On the other hand, when the content of the SiO ₂ component is 40.0% or less, the refractive index is less likely to be lowered, whereby the desired high refractive index can be easily obtained, and the partial dispersion ratio can be suppressed from increasing. Further, by this, it is possible to suppress a decrease in the meltability of the glass raw material. Therefore, the content of the SiO ₂ component is preferably 40.0% as the upper limit, more preferably 35.0% as the upper limit, and still more preferably 32.0% as the upper limit.

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.

When the Nb ₂ O ₅ component contains more than 0%, the refractive index can be increased, the Abbe number and the partial dispersion ratio can be lowered, and any component which is resistant to devitrification can be improved. Therefore, the content of the Nb ₂ O ₅ component is preferably more than 0%, more preferably more than 10.0%, still more preferably more than 15.0%, and still more preferably more than 20.0%.

On the other hand, by setting the content of the Nb ₂ O ₅ component to 40.0% or less, the material cost of the glass can be reduced. Further, it is possible to suppress an increase in the melting temperature at the time of glass production and to reduce devitrification caused by excessive inclusion of the Nb ₂ O ₅ component. Therefore, the content of the Nb ₂ O ₅ component is preferably 40.0% as the upper limit, more preferably 39.0% as the upper limit, still more preferably 36.0% as the upper limit, and further preferably 33.0% as the upper limit. .

As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The sum (mass sum) of the content of the Nb ₂ O ₅ component, the TiO ₂ component and the ZrO ₂ component is preferably 10.0% or more and 60.0% or less.

In particular, by setting the sum to be 10.0% or more, the refractive index can be increased and the devitrification resistance can be improved, so that a glass having a high refractive index and being stable can be easily obtained. Therefore, the mass and (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) are preferably set to 10.0% as the lower limit, more preferably 12.0% as the lower limit, and further preferably 14.0% as the lower limit, and further preferably To set 16.5% to the lower limit.

On the other hand, by making the sum 60.0% or less, devitrification caused by such excessive content can be suppressed. Therefore, the mass and (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) are preferably 60.0% as the upper limit, more preferably 55.0% as the upper limit, and further preferably 50.0% as the upper limit, and further preferably To set 48.0% as the upper limit.

When the TiO ₂ component is contained in an amount exceeding 0%, the refractive index is increased, the Abbe number is lowered, and any component which is resistant to devitrification is improved. Therefore, the content of the TiO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 2.0%, and still more preferably more than 3.0%.

On the other hand, by setting the content of the TiO ₂ component to 20.0% or less, the coloring of the glass can be reduced, and the internal transmittance can be improved. Further, by this, the partial dispersion ratio is less likely to rise, so that a lower partial dispersion ratio which is close to the regular line can be easily obtained. Therefore, the content of the TiO ₂ component is preferably 20.0% or less, more preferably less than 17.0%, still more preferably less than 14.0%, and still more preferably 10.95% or less.

As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

When the content of ZrO ₂ is more than 0%, the refractive index and Abbe number of the glass can be increased, the partial dispersion ratio can be lowered, and any component which is resistant to devitrification can be improved. Moreover, by this, devitrification or coloring at the time of reheating can be reduced. Therefore, the content of the ZrO 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 5.0%, and further preferably set to More than 6.0%.

On the other hand, by setting the content of the ZrO ₂ component to 20.0% or less, devitrification can be reduced, and a more homogeneous glass can be easily obtained. Therefore, the content of the ZrO ₂ component is preferably 20.0% as the upper limit, more preferably 15.0% as the upper limit, and further preferably 11.0% as the upper limit.

As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

When the content of Li ₂ O is more than 0%, the partial dispersion ratio can be lowered, the glass transition point can be lowered, and any component which can melt the glass raw material can be improved. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%, and still more preferably 1.4% or more.

On the other hand, when the content of the Li ₂ O component is 15.0% or less, the decrease in the refractive index can be suppressed, the chemical durability can be prevented from being deteriorated, and the devitrification due to excessive inclusion can be reduced.

Therefore, the content of the Li ₂ O component is preferably 15.0% or less, more preferably 12.0% or less, and still more preferably less than 10.0%.

As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF or the like can be used as a raw material.

When the Na ₂ O component is contained in an amount of more than 0%, the partial dispersion ratio can be lowered, the glass transition point can be lowered, and any component which can improve the meltability of the glass raw material can be obtained. Therefore, the content of the Na ₂ O component is preferably more than 0%, more preferably more than 0.3%, still more preferably more than 0.5%, and still more preferably more than 1.0%.

On the other hand, when the content of the Na ₂ O component is 15.0% or less, the decrease in the refractive index can be suppressed, the chemical durability can be prevented from being deteriorated, and the devitrification caused by excessive inclusion can be reduced.

Therefore, the content of the Na ₂ O component is preferably 15.0% or less, more preferably 12.0% or less, and still more preferably less than 9.0%.

As the Na ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ or the like can be used as a raw material.

The La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component are arbitrary components which can increase the refractive index and reduce the partial dispersion ratio by containing at least one of them. Among them, the content of the La ₂ O ₃ component is preferably set to a lower limit of more than 0%, more preferably 0.5% as a lower limit, and further preferably 0.8% as a lower limit.

On the other hand, when the content of each of the La ₂ O ₃ component and the Y ₂ O ₃ component is 20.0% or less, the increase in the Abbe number can be suppressed, the specific gravity can be reduced, the devitrification can be reduced, and the material cost can be reduced. . Therefore, the content of each of the La ₂ O ₃ component and the Y ₂ O ₃ component is preferably 20.0% or less, more preferably less than 15.0%, still more preferably less than 10.0%, and further preferably Set to less than 8.0%.

In addition, when the content of each of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is 10.0% or less, the increase in the Abbe number can be suppressed, the specific gravity can be reduced, the devitrification can be reduced, and the material cost can be reduced. Therefore, the content of each of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.

As the La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component, La ₂ O ₃ or La(NO ₃ ) ₃ can be used. XH ₂ O (X is an arbitrary integer), Y ₂ O ₃ , YF ₃ , Gd ₂ O ₃ , GdF ₃ , Yb ₂ O ₃ or the like is used as a raw material.

When the MgO component is contained in an amount exceeding 0%, any component of the melting temperature of the glass can be lowered.

On the other hand, by setting the content of the MgO component to 10.0% or less, the decrease in the refractive index can be suppressed, and the devitrification can be reduced. Therefore, the content of the MgO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably less than 1.0%.

As the MgO component, MgO, MgCO ₃ , MgF ₂ or the like can be used as a raw material.

When the CaO component is contained in an amount exceeding 0%, the material cost of the glass can be lowered, the Abbe number can be lowered, the devitrification can be reduced, and any component which can improve the meltability of the glass raw material can be obtained. Therefore, the content of the CaO component is preferably more than 0%, more preferably more than 1.0%, and still more preferably more than 2.0%.

On the other hand, when the content of the CaO component is 15.0% or less, the decrease in the refractive index, the increase in the Abbe number, and the increase in the partial dispersion ratio can be suppressed, and the devitrification can be reduced. Therefore, the content of the CaO component is preferably 15.0% as the upper limit, more preferably 12.0% as the upper limit, still more preferably 10.0% as the upper limit, and further preferably 7.0% as the upper limit.

As the CaO component, CaCO ₃ , CaF ₂ or the like can be used as a raw material.

When the SrO component contains more than 0%, the refractive index can be increased, and any component which is resistant to devitrification can be improved.

In particular, when the content of the SrO component is 10.0% or less, deterioration in chemical durability can be suppressed. Therefore, the content of the SrO component is preferably 10.0% or less, more preferably less than 8.0%, and still more preferably less than 4.0%.

As the SrO component, Sr(NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

When the BaO component is contained in an amount exceeding 0%, the refractive index can be increased, the partial dispersion ratio can be lowered, the devitrification resistance can be improved, the meltability of the glass raw material can be improved, and the glass material can be lowered as compared with other alkaline earth components. Any component of cost. Therefore, the content of the BaO component is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 5.0%. In particular, in the case where the amount of the Nb ₂ O ₅ component is small, the content of the BaO component is preferably more than 10.0%, more preferably more than 20.0%, and still more preferably more than 30.0%.

On the other hand, when the content of the BaO component is 60.0% or less, deterioration in chemical durability or devitrification can be suppressed. Therefore, the content of the BaO component is preferably such that 60.0% is the upper limit, more preferably 55.0% is the upper limit, and further preferably 51.0% is the upper limit. In particular, in the aspect containing the Nb ₂ O ₅ component, the content of the BaO component is preferably set to less than 40.0%, more preferably less than 30.0%, and still more preferably less than 20.0%.

As the BaO component, BaCO ₃ , Ba(NO ₃ ) ₂ or the like can be used as a raw material.

When the ZnO component is contained in an amount exceeding 0%, the partial dispersion ratio is lowered, the devitrification resistance is improved, and any component of the glass transition point can be lowered. Therefore, the content of the ZnO component is preferably more than 0%, more preferably more than 0.5%, still more preferably more than 0.9%.

On the other hand, by setting the content of the ZnO component to 15.0% or less, devitrification or coloring at the time of reheating of the glass is reduced, and chemical durability can be improved. Therefore, the content of the ZnO component is preferably 15.0% or less, more preferably less than 10.0%, still more preferably less than 8.0%, and still more preferably less than 4.0%.

As the raw material, ZnO, ZnF ₂ or the like can be used as the ZnO component.

When the K ₂ O component contains at least one of more than 0%, the meltability of the glass raw material can be improved, and any component of the glass transition point can be lowered.

On the other hand, when the content of the K ₂ O component is 10.0% or less, the partial dispersion ratio can be suppressed from increasing, devitrification can be reduced, and chemical durability can be prevented from being deteriorated. Therefore, the content of 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 the K ₂ O component, K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like can be used as a raw material.

The P ₂ O ₅ component is an optional component which increases the stability of the glass when it contains more than 0%.

On the other hand, by setting the content of the P ₂ O ₅ component to 10.0% or less, devitrification caused by excessive content of the P ₂ O ₅ component can be reduced. Therefore, the content of the P ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.

As the P ₂ O ₅ component, Al(PO ₃ ) ₃ , Ca(PO ₃ ) ₂ , Ba(PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like can be used as a raw material.

When the B ₂ O ₃ component is contained in an amount of more than 0%, it is possible to improve the devitrification resistance by promoting the formation of a stable glass, and to improve the meltability of the glass raw material. Therefore, the content of the B ₂ O ₃ component is preferably set to a lower limit of more than 0%, more preferably 1.0% as a lower limit, and further preferably 2.0% as a lower limit.

On the other hand, when the content of the B ₂ O ₃ component is 15.0% or less, the decrease in the refractive index can be suppressed, and the increase in the partial dispersion ratio can be suppressed. Therefore, the content of the B ₂ O ₃ component is preferably 15.0% or less, more preferably less than 14.0%, still more preferably less than 12.0%, and still more preferably less than 10.0%. Further, it is preferably set to be less than 8.0%, and more preferably set to be less than 6.0%.

As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ can be used. 10H ₂ O, BPO ₄ and the like are used as raw materials.

When the GeO ₂ component contains more than 0%, the refractive index can be increased and the devitrification optional component can be reduced.

On the other hand, by setting the content of the GeO ₂ component to 10.0% or less, the amount of the GeO ₂ component having a high price can be reduced, so that the material cost of the glass can be reduced. Therefore, the content of the GeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.

As the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

When the Ta ₂ O ₅ component contains more than 0%, the refractive index is increased, the Abbe number and the partial dispersion ratio are lowered, and any component which is resistant to devitrification is improved.

On the other hand, when the content of the Ta ₂ O ₅ component is 10.0% or less, the amount of the Ta ₂ O ₅ component used as the rare mineral resource is reduced, and the glass is easily melted at a lower temperature, so that the content can be lowered. The production cost of glass. Further, by this, the devitrification of the glass due to the excessive content of the Ta ₂ O ₅ component can be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably less than 1.0%. In particular, from the viewpoint of lowering the material cost of the glass, the Ta ₂ O ₅ component may not be contained.

As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The WO ₃ component is an optional component which increases the refractive index, lowers the Abbe number, improves the devitrification resistance, and improves the meltability of the glass raw material when it contains more than 0%.

On the other hand, when the content of the WO ₃ component is 10.0% or less, the partial dispersion ratio of the glass is less likely to increase, and the color of the glass is reduced, and the internal transmittance can be improved. Therefore, the content of the WO ₃ component is preferably 10.0% or less as an upper limit, more preferably less than 5.0% as an upper limit, and further preferably less than 3.0% as an upper limit, and more preferably less than 1.0% is set as the upper limit.

As the WO ₃ component, WO ₃ or the like can be used as a raw material.

When the Al ₂ O ₃ component and the Ga ₂ O ₃ component are at least 0%, the chemical durability is improved and the devitrification resistance is improved.

On the other hand, when the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is 10.0% or less, devitrification caused by excessive content of the Al ₂ O ₃ component or the Ga ₂ O ₃ component can be reduced. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, and still more preferably less than 3.0%.

As the raw material of Al ₂ O ₃ component and 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.

When the Bi ₂ O ₃ component contains more than 0%, the refractive index can be increased, the Abbe number can be lowered, and any component of the glass transition point can be lowered.

On the other hand, when the content of the Bi ₂ O ₃ component is 10.0% or less, the partial dispersion ratio is less likely to increase, and the color of the glass can be reduced to increase the internal transmittance. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably less than 1.0%.

As the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

When the TeO ₂ component is contained in an amount exceeding 0%, the refractive index can be increased, the partial dispersion ratio can be lowered, and any component of the glass transition point can be lowered.

On the other hand, by setting the content of the TeO ₂ component to 10.0% or less, the color of the glass can be reduced and the internal transmittance can be improved. Further, by reducing the use of a relatively expensive TeO ₂ component, a glass having a lower material cost can be obtained. Therefore, the content of the TeO ₂ 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 TeO ₂ component, TeO ₂ or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component which promotes defoaming of the self-melting glass and clarifies the glass when it contains more than 0%.

On the other hand, when the content of the Sb ₂ O ₃ component is 1.0% or less, excessive foaming during glass melting is less likely to occur, so that it is difficult to form the Sb ₂ O ₃ component with a melting device (especially a noble metal such as Pt). Alloying. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% as the upper limit, more preferably 0.5% as the upper limit, and further preferably 0.1% as the upper limit. However, when the influence of the optical glass on the environment is emphasized, the Sb ₂ O ₃ component may not be contained.

As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ or Na ₂ H ₂ Sb ₂ O ₇ can be used. 5H ₂ O or the like is used as a raw material.

Further, the component for clarifying and defoaming the glass is not limited to the above-mentioned Sb ₂ O ₃ component, and a known clarifying agent or antifoaming agent in the field of glass production, or a combination thereof may be used.

The ratio of the total amount of the TiO ₂ component and the ZrO ₂ component to the total amount of the Nb ₂ O ₅ component, the TiO ₂ component, and the ZrO ₂ component is preferably 0.10 or more. Thereby, the higher refractive index required can be obtained and the material cost of the glass can be reduced. Therefore, the mass ratio (TiO ₂ + ZrO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) is preferably 0.10 as the lower limit, more preferably 0.15 as the lower limit, and further preferably 0.20. The lower limit is further preferably 0.25 as the lower limit, and further preferably 0.27 as the lower limit.

Furthermore, the upper limit of the mass ratio (TiO ₂ +ZrO ₂ )/(Nb ₂ O ₅ +TiO ₂ +ZrO ₂ ) may also be 1, but it may be less than 1 in terms of further improving the resistance to devitrification. .

The ZrO ₂ component content of Nb ₂ O ₅ with respect to the composition and the ratio of the total amount of the ZrO ₂ component is preferably 0.10 or more. Thereby, the higher refractive index required can be obtained, and the material cost of the glass can be lowered, and the partial dispersion ratio can be further reduced. Therefore, the mass ratio (ZrO ₂ ) / (Nb ₂ O ₅ + ZrO ₂ ) is preferably 0.10 as the lower limit, more preferably 0.14 as the lower limit, and further preferably 0.18 as the lower limit.

Further, the upper limit of the mass ratio (ZrO ₂ ) / (Nb ₂ O ₅ + ZrO ₂ ) may be 1, but it may be less than 1 from the viewpoint of further improving the resistance to devitrification.

The sum (mass sum) of the content of the Ln ₂ O ₃ component (wherein Ln is selected from one or more of the group consisting of La, Gd, Y, and Yb) is preferably 20.0% or less. Thereby, the devitrification of the glass can be reduced, the increase in the Abbe number can be suppressed, and the material cost of the glass can be reduced. Therefore, the mass of the Ln ₂ O ₃ component is preferably 20.0% or less, more preferably less than 15.0%, still more preferably less than 10.0%, and further preferably less than 8.5%. .

The total amount of the Nb ₂ O ₅ component and the Ln ₂ O ₃ component (wherein Ln is selected from the group consisting of Y, La, Gd, and Yb) is preferably 5.0% or more and 40.0% or less.

In particular, by setting the total amount to 5.0% or more, the refractive index can be increased and the devitrification of the glass can be reduced. Therefore, the mass and (Nb ₂ O ₅ + Ln ₂ O ₃ ) are preferably 5.0% as the lower limit, more preferably 6.0% as the lower limit, and further preferably 7.5% as the lower limit.

On the other hand, by making the total amount 40.0% or less, a desired higher refractive index can be obtained, and the material cost of the glass can be lowered. Therefore, the mass and (Nb ₂ O ₅ + Ln ₂ O ₃ ) are preferably 40.0% as the upper limit, more preferably 35.0% as the upper limit, and further preferably 33.0% as the upper limit.

The ratio of the content of the ZrO ₂ component to the total amount of the Nb ₂ O ₅ component and the Ln ₂ O ₃ component (wherein the Ln is selected from the group consisting of Y, La, Gd, and Yb) is preferably a ratio. It is 0.10 or more and 3.00 or less.

In particular, by making the ratio 0.10 or more, a desired higher refractive index can be obtained, and the material cost of the glass can be lowered, and the partial dispersion ratio can be further reduced. Therefore, the mass ratio (ZrO ₂ )/(Nb ₂ O ₅ +Ln ₂ O ₃ ) is preferably 0.10 as the lower limit, more preferably 0.135 as the lower limit, and further preferably 0.15 as the lower limit, and thus more preferably Preferably, 0.19 is set as the lower limit, and further preferably 0.215 is set as the lower limit, and further preferably 0.224 is set as the lower limit.

On the other hand, by making the ratio 3.00 or less, the devitrification of the glass can be reduced. Therefore, the mass ratio (ZrO ₂ )/(Nb ₂ O ₅ +Ln ₂ O ₃ ) is preferably set to 3.00 as the upper limit, more preferably 2.00 as the upper limit, and further preferably 1.50 as the upper limit, and thus more preferably Jia Wei sets 1.00 as the upper limit.

The sum (mass sum) of the content of the RO component (wherein R is selected from one or more of the group consisting of Mg, Ca, Sr, and Ba) is preferably 60.0% or less. Thereby, the devitrification of the glass caused by the excessive content of the components can be reduced. Therefore, the mass of the RO component is preferably 60.0% as the upper limit, more preferably 55.0% as the upper limit, and further preferably 51.0% as the upper limit.

On the other hand, from the viewpoint of improving the meltability of the glass raw material and reducing the devitrification, the mass of the RO component is preferably more than 0%, more preferably 1.0% or more, and further preferably set to 2.0% or more.

The total amount of the Nb ₂ O ₅ component and the BaO component is preferably 10.0% or more and 65.0% or less.

In particular, by setting the total amount to 10.0% or more, the refractive index can be increased, the partial dispersion ratio can be lowered, and the devitrification resistance can be improved. Therefore, the mass and (Nb ₂ O ₅ +BaO) are preferably such that 10.0% is the lower limit, more preferably 20.0% is the lower limit, and further preferably 25.0% is the lower limit.

On the other hand, by making the total amount 65.0% or less, the devitrification of the glass can be reduced. Therefore, the mass and (Nb ₂ O ₅ +BaO) are preferably 65.0% as the upper limit, more preferably 55.0% as the upper limit, and further preferably 50.0% as the upper limit.

The sum (mass 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 30.0% or less. Thereby, the refractive index of the glass can be prevented from being lowered, and the devitrification at the time of glass formation can be reduced. Therefore, the total content of the Rn ₂ O components is preferably 30.0% or less as the upper limit, more preferably 25.0% as the upper limit, still more preferably 20.0% as the upper limit, and further preferably 16.0%. Upper limit.

On the other hand, from the viewpoint of improving the meltability of the glass raw material and lowering the glass transition point, the mass of the Rn ₂ O component is preferably more than 0%, more preferably more than 1.0%, and further preferably It is set to exceed 1.7%.

The total amount (mass sum) of the B ₂ O ₃ component and the Ln ₂ O ₃ component (wherein Ln is selected from the group consisting of Y, La, Gd, and Yb) is preferably 30.0% or less. Thereby, the specific gravity can be reduced and a higher transmittance can be obtained. Therefore, the mass and (B ₂ O ₃ + La ₂ O ₃ ) are preferably such that 30.0% is the upper limit, more preferably 25.0% is the upper limit, and further preferably 20.0% is the upper limit, and further preferably It is preferable to set 15.0% as an upper limit, and it is preferable to set 12.0% as an upper limit, and it is preferable to set 11.0% as an upper limit.

The ratio of the total amount of the B ₂ O ₃ component and the Ln ₂ O ₃ component (wherein Ln is selected from one or more of the group consisting of Y, La, Gd, and Yb) to the content of the ZrO ₂ component is preferred. It is 0.10 or more and 10.00 or less.

In particular, by making the ratio 0.10 or more, the devitrification of the glass can be reduced. Therefore, the mass ratio ZrO ₂ /(B ₂ O ₃ +Ln ₂ O ₃ ) is preferably 0.10 as the lower limit, more preferably 0.15 as the lower limit, and further preferably 0.25 as the lower limit.

On the other hand, by setting the ratio to 10.00 or less, the specific gravity can be reduced, a high transmittance can be obtained, and the partial dispersion ratio can be further reduced. Therefore, the mass ratio ZrO ₂ /(B ₂ O ₃ +Ln ₂ O ₃ ) is preferably set to 10.00 as the lower limit, more preferably 5.00 is set as the lower limit, and further preferably 4.00 is set as the lower limit, and further preferably 3.00 is set as the lower limit, and further preferably 2.50 is set as the lower limit, and further preferably 1.70 is set as the lower limit.

The ratio of the content of the Na ₂ O component to the content of the Li ₂ O component is preferably 0.01 or more and 10.00 or less.

In particular, by making the ratio 0.01 or more, devitrification of the glass can be reduced. Therefore, the mass ratio Na ₂ O/Li ₂ O is preferably such that 0.01 is the lower limit, more preferably 0.03 is the lower limit, and further preferably 0.05 is set as the lower limit.

On the other hand, by setting the ratio to 10.00 or less, the partial dispersion ratio can be further reduced. Therefore, the mass ratio Na ₂ O/Li ₂ O is preferably 10.00 as an upper limit, more preferably 5.00 is an upper limit, further preferably 3.00 is an upper limit, and further preferably 1.50 is an upper limit.

<About ingredients that should not be included>

Next, the components which should not be contained in the optical glass of the present invention and the components which are not preferable are described.

Other components may be added as needed within the scope of the characteristics of the glass of the invention of the present invention. However, each of the transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo other than Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu is in a separate form. When the composite form contains a small amount, the glass is colored and absorbs a specific wavelength in the visible light range. Therefore, it is preferably substantially not contained in the optical glass having a wavelength in the visible light region.

Further, since a lead compound such as PbO or an arsenic compound such as As ₂ O ₃ is a component having a high environmental load, it is preferably substantially not contained, that is, it is completely excluded except for unavoidable mixing.

Furthermore, the components of Th, Cd, Tl, Os, Be, and Se have been harmful in recent years. Chemical materials, and reduce the tendency to use, not only the manufacturing steps of glass, but also the processing steps, and the treatment after productization, must take measures for environmental countermeasures. Therefore, when it is important to pay attention to the influence of the environment, it is preferable that it does not substantially contain such.

[Production method]

The optical glass of the present invention is produced, for example, by the following method. In other words, the raw materials are uniformly mixed so that the respective components are within a specific content range, and the produced mixture is introduced into platinum crucible, quartz crucible or alumina crucible to be substantially melted. Put it into a gold crucible, platinum crucible, platinum alloy crucible or crucible, melt it in the temperature range of 1100~1400 °C for 3 to 5 hours, stir it to homogenize it, defoam, etc., and then reduce it to 1000~ After the temperature of 1400 ° C, the mixture is agitated to remove the veins, cast into the mold and slowly cooled.

<physical property>

The optical glass of the present invention has a high refractive index and an Abbe number of a specific range.

The refractive index (n _d ) of the optical glass of the present invention is preferably set to a lower limit of 1.65, more preferably 1.68 as a lower limit, still more preferably 1.70 as a lower limit, and further preferably 1.72 as a lower limit. The upper limit of the refractive index is preferably 1.90, more preferably 1.87, still more preferably 1.85, still more preferably 1.82, still more preferably 1.80.

The Abbe number (ν _d ) of the optical glass of the present invention is preferably such that 45 is the upper limit, more preferably 40 is the upper limit, and further preferably 38 is the upper limit. On the other hand, the Abbe number (ν _d ) of the optical glass of the present invention is preferably such that 25 is the lower limit, more preferably 28 is set as the lower limit, and further preferably 30 is set as the lower limit.

The optical glass of the present invention having such a refractive index and an Abbe number is useful for optical design, and particularly, it is possible to realize particularly high imaging characteristics and the like, and it is possible to realize miniaturization of an optical system, thereby expanding the degree of freedom in optical design.

Here, the optical glass of the present invention preferably has a relationship between a refractive index (nd) and an Abbe number (νd) satisfying (-0.02 νd + 2.30) ≦ nd ≦ (-0.02 νd + 2.60). In the present invention, a specific group The refractive index (nd) and the Abbe number (νd) of the formed glass satisfy this relationship, whereby a more stable glass can be obtained.

Therefore, 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 νd + 2.30), and more preferably satisfy nd ≧ (-0.02 νd + 2.35). Further, it is preferable to satisfy the relationship of nd ≧ (-0.02 νd + 2.38), and further preferably to satisfy the relationship of nd ≧ (-0.02 νd + 2.40).

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 νd + 2.60), and more preferably satisfy nd ≦ (-0.02 νd + The relationship of 2.58) is further preferably such that the relationship of nd ≦ (-0.02 νd + 2.55) is satisfied, and further preferably the relationship of nd ≦ (-0.02 νd + 2.52) is satisfied.

The optical glass of the present invention has a lower partial dispersion ratio (θg, F).

More specifically, the partial dispersion ratio (θg, F) of the optical glass of the present invention is preferably an upper limit of 0.615, more preferably an upper limit of 0.610, and still more preferably an upper limit of 0.600. The lower limit of the partial dispersion ratio (θg, F) is preferably 0.550, more preferably 0.560, still more preferably 0.570.

Further, the partial dispersion ratio (θg, F) of the optical glass of the present invention preferably satisfies (-0.0025 × νd + 0.645) ≦ (θg, F) ≦ (-0.0025 × νd) with the Abbe number (ν _d ). +0.695) relationship.

Thereby, an optical glass having a lower partial dispersion ratio (θg, F) is obtained, and thus an optical element formed from the optical glass contributes to a reduction in chromatic aberration of the optical system.

Therefore, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (νd) preferably satisfy the relationship of θg, F ≧ (-0.0025 × νd + 0.645), and more preferably satisfy θg. The relationship of F ≧ (-0.0025 × νd + 0.655) is more preferably satisfied by the relationship of θg, F ≧ (-0.0025 × νd + 0.660).

On the other hand, in the optical glass of the present invention, the partial dispersion ratio (θg, F) and the Abbe number (νd) preferably satisfy the relationship of θg, F≦ (-0.0025 × νd + 0.695), and more preferably satisfy The relationship between θg and F ≦ (-0.0025 × νd + 0.685) is more preferably satisfied by the relationship of θg, F ≦ (-0.0025 × νd + 0.680).

Furthermore, especially in the region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of the glass is generally higher than the regular line value, and the Abbe number (ν _d ) is taken on the horizontal axis. When the vertical axis takes a partial dispersion ratio (θg, F), the relationship between the partial dispersion ratio (θg, F) of the glass and the Abbe number (ν _d ) is expressed by a curve having a slope larger than a regular line. In the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ), the partial dispersion ratio (θg, F) is smaller than usual by specifying the relationship using a straight line having a slope larger than a regular line. Glass of glass.

The optical glass of the present invention preferably has less coloration.

In particular, when the optical glass of the present invention is expressed by the transmittance of glass, the wavelength (λ ₇₀ ) at which the spectral transmittance is 70% in the sample having a thickness of 10 mm is preferably 460 nm or less, more preferably 430 nm or less, and further preferably Below 420nm.

Further, the optical glass of the present invention exhibits a wavelength (λ ₅ ) of 5% of the spectral transmittance in a sample having a thickness of 10 mm, preferably 400 nm or less, more preferably 380 nm or less, still more preferably 360 nm or less.

Further, the optical glass of the present invention exhibits a wavelength (λ ₈₀ ) at a spectral transmittance of 80% in a sample having a thickness of 10 mm, preferably 550 nm or less, more preferably 520 nm or less, still more preferably 500 nm or less.

Thereby, the absorption end of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass in the visible light range is improved. Therefore, the optical glass can be preferably used as a material of an optical element 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 5.00 [g/cm ³ ] or less. Thereby, the quality of the optical element or the optical device using the same is reduced, and thus the weight of the optical device can be reduced. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.00 as the upper limit, more preferably 4.80 as the upper limit, still more preferably 4.50 as the upper limit, and further preferably 4.30 as the upper limit. Further, in many cases, the specific gravity of the optical glass of the present invention is approximately 2.50 or more, more specifically 2.80 or more, and more specifically 3.00 or more.

The specific gravity of the optical glass of the present invention is measured based on the Japanese Optical Glass Industrial Standards JOGIS05-1975 "Method for Measuring the Specific Gravity of Optical Glass".

The optical glass of the present invention preferably has a glass transition point of 650 ° C or less. Thereby, the glass is softened at a lower temperature, so that the glass can be molded at a lower temperature. Moreover, the oxidation of the mold for press molding can be reduced to achieve a long service life of the mold. Therefore, the glass transition point of the optical glass of the present invention is preferably 650 ° C as the upper limit, more preferably 620 ° C as the upper limit, more preferably 600 ° C as the upper limit, and further preferably 585 ° C. The upper limit.

Further, the lower limit of the glass transition point of the optical glass of the present invention is not particularly limited, and the glass transition point of the optical glass of the present invention preferably has 460 ° C as the lower limit, more preferably 480 ° C as the lower limit, and thus Jia will set 500 °C as the lower limit.

The optical glass of the present invention is preferably high in devitrification resistance (hereinafter sometimes referred to as "devitrification resistance" in the specification). Thereby, the transmittance reduction due to crystallization of the glass during the production of the glass is suppressed, and therefore the optical glass can be preferably used for an optical element that transmits visible light such as a lens. Further, as a standard indicating that the devitrification resistance at the time of glass production is high, for example, a liquidus temperature is low.

[Preforms and optical components]

For example, a glass molded body can be produced from the produced optical glass by a method of press molding such as reheat press molding or precision press molding. In other words, a preform for press molding can be produced from an optical glass, and the preform can be subjected to reheat molding, followed by polishing to prepare a glass molded body, or a preform obtained by, for example, polishing. The glass molded body was produced by precision press molding. Furthermore, the method of producing a glass molded body is not limited to these methods.

The glass molded body produced in this manner is useful for various optical components. Among them, it is particularly preferable to use it for an optical element such as a lens or a crucible. Thereby, the color blur caused by the chromatic aberration under the transmitted light of the optical system provided with the optical element is reduced. Therefore, when the optical element is used in a camera, the object to be imaged can be more accurately expressed, and when the optical element is used in a projector, the desired image can be projected in higher definition.

[Examples]

The composition of the examples (No. 1 to No. 15) and the comparative example (No. A) of the present invention, and the refractive index (n _d ), the Abbe number (ν _d ), and the partial dispersion ratio (θg, F) The spectral transmittance shows that the wavelengths of 5%, 70%, and 80% (λ ₅ , λ ₇₀ , λ ₈₀ ), the glass transition point (Tg), and the specific gravity are shown in Tables 1 to 2. Furthermore, the following examples are for illustrative purposes, and the invention is not limited to the examples.

In the glass of the examples and the comparative examples, as the raw materials of the respective components, oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric compounds, and the like which are each equivalent are selected for use in usual optical glass. The high-purity raw material is weighed and uniformly mixed so as to have a ratio of the composition of each of the examples and the comparative examples shown in the table, and then introduced into a platinum crucible, and the electric furnace is used according to the melting difficulty of the glass composition. Melt in the temperature range of 1100~1400°C for 3~5 hours, stir it to homogenize and defoam, etc., then lower the temperature to 1000~1400°C, stir it to homogenize it, then cast it to the mold and slowly cool it. And make glass.

The refractive index (n _d ), the Abbe number (ν _d ), and the partial dispersion ratio (θg, F) of the glass of the examples and the comparative examples were measured based on the Japan Optical Glass Industry Association standard JOGIS01-2003.

Then, based on the obtained values of the refractive index (n _d ) and the Abbe number (ν _d ), the intercept b when the slope a in the relational expression (n _d =−a×ν _d +b) is 0.02 is obtained. .

Further, based on the obtained Abbe number (ν _d ) and the partial dispersion ratio (θg, F), the slope a' in the relational expression (θg, F = -a' × ν _d + b') is obtained as Intercept b' at 0.0025.

Further, the glass used in the measurement was obtained by treating the slow cooling rate to -25 ° C / hr and using a slow cooling furnace.

The transmittance of the glass of the examples and the comparative examples was measured in accordance with the Japan Optical Glass Industry Association standard JOGIS02. Further, in the present invention, the presence or absence of the color of the glass is determined by measuring the transmittance of the glass. Specifically, for the opposite parallel polished product having a thickness of 10 ± 0.1 mm, the light transmittance of 200 to 800 nm is measured in accordance with JIS Z8722, and λ ₅ (wavelength at a transmittance of 5%) and λ ₇₀ (transmittance 70%) are obtained. The wavelength of time) and λ ₈₀ (wavelength at 80% transmittance).

The glass transition point (Tg) of the glass of the examples and the comparative examples is determined by measuring the relationship between the temperature and the elongation of the sample according to the Japanese Optical Glass Industrial Standards JOGIS08-2003 "Method for Measuring Thermal Expansion of Optical Glass". The obtained thermal expansion curve was obtained.

The specific gravity of the glass of the examples and the comparative examples was measured based on the Japanese Optical Glass Industrial Standards JOGIS05-1975 "Method for Measuring the Specific Gravity of Optical Glass".

As shown in the tables, the partial dispersion ratio (θg, F) of the optical glass of the embodiment of the present invention is 0.615 or less, and more specifically 0.600 or less, which is within a desired range.

Here, the partial dispersion ratio (θg, F) and the Abbe number (νd) of the optical glass of the embodiment of the present invention satisfy (-0.0025 × νd + 0.645) ≦ (θg, F) ≦ (-0.0025 × νd + 0.695 The relationship, in more detail, satisfies the relationship of (-0.0025 × νd + 0.660) ≦ (θg, F) ≦ (-0.0025 × νd + 0.680). That is, the relationship between the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) of the glass in the embodiment of the present invention is as shown in Fig. 2 .

On the other hand, the partial dispersion ratio (θg, F) of the glass of Comparative Example (No. A) of the present invention exceeded 0.615. Therefore, it is apparent that the optical glass of the embodiment of the present invention has a partial dispersion ratio (θg, F) smaller than that of the glass of the comparative example.

The refractive index (n _d ) of the optical glass of the embodiment of the present invention is 1.65 or more, more specifically 1.74 or more, and the refractive index (n _d ) is 1.90 or less, and more specifically 1.80 or less. Within the scope of the need.

Further, the optical glass of the embodiment of the present invention has an Abbe number (ν _d ) of 25 or more, more specifically 30 or more, and the Abbe number (ν _d ) is 45 or less, and more specifically 38. Below, within the required range.

Here, the refractive index (nd) and the Abbe number (νd) of the optical glass of the embodiment of the present invention satisfy the relationship of (-0.02 νd + 2.30) ≦ nd ≦ (-0.02 νd + 2.60), and more specifically, Satisfy the relationship of (-0.02νd+2.39)≦nd≦(-0.02νd+2.52). Further, the relationship between the refractive index (nd) and the Abbe number (νd) of the glass of the embodiment of the present invention is shown in Fig. 3.

Therefore, it is clear that the optical glass of the embodiment reduces the material cost by the content of the Nb ₂ O ₅ component, and the refractive index (n _d ) and the Abbe number (ν _d ) are all within a desired range. And an optical glass having a partial dispersion ratio (θg, F) is small.

Further, λ ₇₀ (wavelength at a transmittance of 70%) of the optical glass of the embodiment of the present invention is 460 nm or less, and more specifically 420 nm or less.

Further, in the optical glass of the embodiment of the present invention, λ ₅ (wavelength at a transmittance of 5%) is 400 nm or less, and more specifically 360 nm or less.

Further, λ ₈₀ (wavelength at a transmittance of 80%) of the optical glass of the embodiment of the present invention is 550 nm or less, and more specifically 480 nm or less.

Therefore, it is clear that the optical glass of the embodiment of the present invention has a high transmittance to visible light and is not easily colored.

Further, the specific gravity of the optical glass of the examples is 5.00 or less, and more specifically 4.30 or less, which is within the required range.

Further, since the glass transition point of the optical glass of the example is 650 ° C or lower, and more specifically 580 ° C or lower, it is presumed that the glass can be press-formed at a lower temperature.

Further, the lens preform was formed using the optical glass of the example, and the lens preform was subjected to press molding, and as a result, it was stably processed into various lens shapes.

The present invention has been described in detail above with reference to the preferred embodiments of the invention.

Claims (13)

An optical glass containing, by mass%, 10.0 to 40.0% of SiO ₂ component, 40.0% or less of Nb ₂ O ₅ component, and mass (Nb ₂ O ₅ +TiO ₂ +ZrO ₂ ) of 10.0 to 60.0%, and The refractive index (n _d ) of 1.65 or more and 1.90 or less, the Abbe number (ν _d ) of 25 or more and 45 or less, and the partial dispersion ratio (θg, F) of 0.615 or less. The optical glass of claim 1, wherein the TiO ₂ component is 0 to 20.0% by mass%, the ZrO ₂ component is 0 to 20.0%, the Li ₂ O component is 0 to 15.0%, and the Na ₂ O component is 0 to 15.0%. The optical glass of claim 1 or 2, wherein the La ₂ O ₃ component is 0 to 20.0% by mass%, the Gd ₂ O ₃ component is 0 to 10.0%, and the Y ₂ O ₃ component is 0 to 20.0% Yb ₂ O ₃ component is 0 to 10.0% of MgO component is 0 to 10.0% of CaO component is 0 ~ 15.0% SrO content is 0 to 10.0% of BaO content is 0 ~ 60.0% ZnO content is 0 ~ 15.0% K ₂ O content is 0 to 10.0% P ₂ O ₅ component is 0~10.0% B ₂ O ₃ component is 0~15.0% GeO ₂ component is 0~10.0% Ta ₂ O ₅ component is 0~10.0% WO ₃ component is 0~10.0% Al ₂ O ₃ The composition is 0~10.0% Ga ₂ O ₃ is 0~10.0% Bi ₂ O ₃ is 0~10.0% TeO ₂ is 0~10.0% SnO ₂ is 0~5.0% Sb ₂ O ₃ is 0~ 1.0%. The optical glass according to any one of claims 1 to 3, wherein the mass ratio (TiO ₂ + ZrO ₂ ) / (Nb ₂ O ₅ + TiO ₂ + ZrO ₂ ) is 0.10 or more. The optical glass according to any one of claims 1 to 4, wherein the mass ratio (ZrO ₂ ) / (Nb ₂ O ₅ + ZrO ₂ ) is 0.10 or more. The optical glass according to any one of claims 1 to 5, wherein the mass of the Ln ₂ O ₃ component (wherein Ln is one or more selected from the group consisting of Y, La, Gd, and Yb) is 20.0. %the following. The optical glass according to any one of claims 1 to 6, wherein the mass ratio (ZrO ₂ ) / (Nb ₂ O ₅ + Ln ₂ O ₃ ) is 0.10 or more and 3.00 or less. The optical glass according to any one of claims 1 to 7, wherein the mass of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is 60.0% or less. The optical glass according to any one of claims 1 to 8, wherein the mass of the Rn ₂ O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is 30.0% or less. The optical glass according to any one of claims 1 to 9, wherein the spectral transmittance shows that 70% of the wavelength (λ ₇₀ ) is 460 nm or less. An optical element comprising the optical glass of any one of claims 1 to 10. A preform for polishing processing and/or precision press molding, comprising The optical glass of any one of items 1 to 10. An optical element formed by precision pressing a preform as claimed in claim 12.