TWI766992B - Optical Glass, Preforms, and Optical Components - Google Patents

Abstract

The subject of the present invention is to provide an optical glass, a preform and an optical element using the optical glass; wherein the optical glass has optical properties of high refractive index and low dispersion, and the value of the temperature coefficient of the relative refractive index is high, It can help to correct the effect of temperature change on imaging characteristics. The optical glass contains 10.0% to 45.0% of B ₂ O ₃ component, more than 0% to 15.0% of SiO ₂ component, more than 15.0% to 60.0% of ZnO component and 10% to 50.0% of La ₂ O ₃ component in mass %, And the temperature coefficient (40°C to 60°C) of the relative refractive index (589.29 nm) is in the range of +8.0×10 ^-6 (°C ^-1 ) to +16.0×10 ^-6 (°C ^-1 ).

Description

Optical Glass, Preforms, and Optical Components

The present invention relates to optical glasses, preforms, and optical elements.

In recent years, optical components assembled in automotive optical equipment such as in-vehicle cameras, or optical components assembled in optical equipment such as projectors, computers, laser printers, and playback equipment that generate a lot of heat have been used at higher temperatures. environmental conditions continue to increase. In such a high-temperature environment, the temperature of the optical elements constituting the optical system tends to fluctuate greatly during use, and it often occurs that the temperature reaches 100° C. or higher. At this time, the negative effects of temperature fluctuations on the imaging characteristics of the optical system are too great to be ignored. Therefore, it is desirable to configure an optical system that is difficult to affect imaging characteristics and the like even if temperature fluctuations occur.

As a material for an optical element constituting an optical system, a high refractive index glass having a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 28 or more and 55 or less is very much demanded. As such a high-refractive-index glass, for example, glass compositions represented by Patent Documents 1 to 2 are known.

[Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2011-178571.

Patent Document 2: Japanese Patent Laid-Open No. 2014-047099.

When constructing an optical system that is not easily affected by temperature fluctuations, the following two optical elements are used together: the refractive index becomes lower when the temperature rises, and the temperature coefficient of the relative refractive index becomes negative. Element; an optical element composed of glass whose refractive index increases as the temperature increases, and the temperature coefficient of the relative refractive index becomes a positive value, so that the influence of temperature change on imaging characteristics, etc. can be corrected, so it is preferable.

In particular, as a high refractive index glass having a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 28 or more and 55 or less, from the viewpoint of helping to correct the influence of temperature changes on imaging characteristics In other words, it is ideal to have a glass with a large temperature coefficient of the relative refractive index, more specifically, a glass with a positive temperature coefficient of the relative refractive index, or a glass with a large absolute value of the temperature coefficient of the relative refractive index. Glass.

The present invention is made in view of the above-mentioned problems, and its object is to provide an optical glass, a preform material and an optical element using the optical glass, wherein the optical glass has optical properties of high refractive index and low dispersion , and the value of the temperature coefficient of the relative refractive index is high, which can help to correct the influence of the temperature change on the imaging characteristics.

In order to solve the above-mentioned problems, the present inventors have concentrated on the results of accumulated test studies and found that by adjusting the contents of each component represented by the B ₂ O ₃ component, the SiO ₂ component, the ZnO component, and the La ₂ O ₃ component, the relative relative The numerical value of the temperature coefficient of the refractive index is high, and the present invention has been completed. Specifically, the present invention provides the following.

(1) An optical glass containing, in mass %, a B2O3 component _of 10.0% to 45.0%, a _SiO2 component of more than ₀ % to 15.0%, a ZnO component of more than 15.0% to 60.0%, and a _La2O3 component of 10.0 _% % to 50.0%, and the temperature coefficient (40°C to 60°C) of the relative refractive index (589.29nm) is in the range of +8.0×10 ^-6 (°C ^-1 ) to +16.0×10 ^-6 (°C ^-1 ) Inside.

(2) The optical glass according to (1), wherein the mass sum (Ta ₂ O ₅ +Nb ₂ O ₅ +WO ₃ ) is less than 7.0%.

(3) The optical glass according to (1) or (2), which has a refractive index (n _d ) of 1.70 or more and 1.90 or less, and has an Abbe number (ν _d ) of 28 or more and 55 or less.

(4) A preform comprising the optical glass described in any one of (1) to (3).

(5) An optical element comprising the optical glass described in any one of (1) to (3).

(6) An optical device including the optical element described in (5).

According to the present invention, it is possible to obtain an optical glass having high refractive index and low dispersion optical properties, and having a high temperature coefficient relative to the refractive index, which can help to correct the influence of temperature changes on imaging properties. , and preforms and optical elements using the optical glass.

The optical glass of the present invention contains, in mass %, a B ₂ O ₃ component of 10.0% to 45.0%, a SiO ₂ component of more than 0% to 15.0%, a ZnO component of more than 15.0% to 60.0%, and a La ₂ O ₃ component of 10.0% To 50.0%, and by adjusting the content of each component represented by the B ₂ O ₃ component, the SiO ₂ component, the ZnO component, and the La ₂ O ₃ component, the temperature coefficient of the relative refractive index will be low. Therefore, it is possible to obtain an optical glass with high refractive index and low dispersion optical properties, and with a high temperature coefficient of the relative refractive index, which can help to correct the influence of temperature changes on imaging properties.

Hereinafter, 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 embodiment, and can be implemented with appropriate changes within the scope of the object of the present invention. In addition, although the description of the part which repeated description may be abbreviate|omitted suitably, it does not limit the meaning of invention by this.

[glass composition]

The composition range of each component which comprises the optical glass of this invention is as follows. In this specification, the content of each component is expressed in mass % relative to the total mass of the oxide-converted composition, unless otherwise specified. Here, the "composition in terms of oxides" means that when all the oxides, complex salts, metal fluorides, etc. used as the raw materials for the glass constituents of the present invention are decomposed into oxides at the time of melting, the resulting The total mass of the oxides is set to 100 mass %, and the composition of the various components contained in the glass is represented.

<About essential ingredients and optional ingredients>

The B ₂ O ₃ component is an essential component as a glass-forming oxide in the optical glass of the present invention containing a large amount of rare earth oxides. _In particular, by making content _of a B2O3 component 10.0% or more, the devitrification resistance of glass can be improved, and the Abbe number of glass can be raised. Therefore, the lower limit of the content of the B ₂ O ₃ component is preferably 10.0% or more, preferably 15.0% or more, and more preferably 20.0% or more.

On the other hand, by setting the content of the B ₂ O ₃ component to be 45.0% 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 45.0% or less, preferably less than 40.0%, more preferably less than 38.0%, and still more preferably less than 25.0%.

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

When the content of SiO ₂ is more than 0%, the viscosity of molten glass can be increased, and the coloring of glass can be reduced. In addition, this component can also improve glass stability, and it is easy to obtain glass that can withstand mass production. Therefore, the content of the SiO ₂ component is preferably greater than 0%, preferably greater than 1.0%, more preferably greater than 3.0%, and even more preferably greater than 5.0%.

On the other hand, by making content of a _SiO2 component 15.0 % or less, the raise of a glass transition point can be suppressed, and the fall of a refractive index can be suppressed. Therefore, the content of the SiO ₂ component is preferably less than 15.0%, preferably less than 10.0%, more preferably less than 8.0%.

As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

When the content of ZnO is more than 15.0%, it can improve the solubility of raw materials, promote the defoaming of the melted glass, improve the stability of the glass, and increase the temperature coefficient of the relative refractive index. Furthermore, this ingredient can also reduce the glass transition point and can improve chemical durability. Therefore, the content of the ZnO component is preferably greater than 15.0%, preferably greater than 18.0%, and more preferably greater than 20.0%.

On the other hand, by making content of a ZnO component 60.0 % or less, the refractive index fall of glass can be suppressed, and devitrification by an excessively low viscosity can be reduced. Therefore, the content of the ZnO component is preferably 60.0% or less, preferably less than 50.0%, more preferably less than 45.0%, and still more preferably less than 35.0%.

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

The La ₂ O ₃ component is an essential component for increasing the refractive index and Abbe number of glass. Therefore, the content of the La ₂ O ₃ component is preferably 10.0% or more, preferably 15.0% or more, more preferably more than 20.0%, and still more preferably more than 25.5%.

On the other hand, by making content _of a _La2O3 component 55.0% or less, devitrification can be reduced by improving the stability of glass, and it can suppress that an Abbe number rises more than necessary. Moreover, the meltability of glass raw material can be improved. Therefore, the content of the La ₂ O ₃ component is preferably 55.0% or less, preferably less than 50.0%, more preferably less than 45.0%.

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

When the content of TiO ₂ is greater than 0%, the refractive index of the glass can be increased, and the stability can be improved by lowering the liquidus temperature of the glass. Therefore, the content of the TiO ₂ component is preferably greater than 0%, preferably greater than 1.0%, and more preferably greater than 3.0%.

On the other hand, by setting the content of the TiO ₂ component to be 15.0% or less, devitrification due to excess TiO ₂ component content can be reduced, and a reduction in the transmittance of the glass to visible light (especially wavelengths of 500 nm or less) can be suppressed. . In addition, a decrease in the Abbe number can be suppressed by this. Therefore, the content of the TiO ₂ component is preferably 15.0% or less, preferably 13.0% or less, and more preferably 10.0% 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 glass can be increased, and the devitrification resistance can be improved. Therefore, the content of the ZrO ₂ component is preferably greater than 0%, preferably greater than 1.0%, and more preferably greater than 2.0%.

On the other hand, by making content of a ZrO ₂ component 10.0 % or less, devitrification by excess content of ZrO ₂ component can be reduced. Therefore, the content of the ZrO ₂ component is preferably less than 10.0%, preferably less than 8.0%, more preferably less than 5.0%.

As the ZrO ₂ component, ZrO ₂ , ZrF ₄ and the like can be used as raw materials.

When the content of Nb ₂ O ₅ is greater than 0%, the refractive index of the glass can be increased, and the devitrification resistance can be improved by lowering the liquidus temperature of the glass.

_On the other hand, by making content of a _Nb2O5 component less than 10.0%, the material cost of glass can be reduced. In addition, devitrification due to excess Nb ₂ O ₅ component content can be reduced, and reduction in transmittance of glass with respect to visible light (especially wavelengths of 500 nm or less) can be suppressed. In addition, a decrease in Abbe's number can be suppressed by this. Therefore, the content of Nb ₂ O ₅ is preferably less than 10.0%, preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably less than 0.5 %, and still more preferably less than 0.1%. In particular, from the viewpoint of material cost reduction, it is preferable not to contain the Nb ₂ O ₅ component.

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

When the content of WO ₃ component is more than 0%, in addition to reducing the coloring of glass caused by other high refractive index components, it can also increase the refractive index, reduce the glass transition point, and improve the devitrification resistance.

On the other hand, by making content _of WO3 component less than 10.0%, the material cost of glass can be reduced. Moreover, the glass coloration by _WO3 component can be reduced, and visible light transmittance can be improved. Therefore, the content of the WO ₃ component is preferably less than 10.0%, preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably less than 0.5% , and still more preferably less than 0.1%. In particular, from the viewpoint of material cost reduction, it is preferable not to contain the WO ₃ component.

_WO3 component, _WO3 etc. can be used as a raw material.

When the content of Y ₂ O ₃ is greater than 0%, in addition to maintaining a high refractive index and a high Abbe number, the material cost of the glass can also be reduced, and compared with other rare earth components, the arbitrary proportion of the specific gravity of the glass can be reduced. Element. Therefore, the content of the Y ₂ O ₃ component is preferably greater than 0%, preferably greater than 3.0%, and more preferably greater than 5.0%.

_On the other hand, by making content of a _Y2O3 component 20.0% or less, the refractive index of glass can be suppressed from falling, and the stability of glass can be improved. Moreover, the meltability deterioration of glass raw material can be suppressed. Therefore, the content of the Y ₂ O ₃ component is preferably less than 20%, preferably less than 18.0%, more preferably less than 15.0%, and still more preferably less than 13.0%.

For the Y ₂ O ₃ component, Y ₂ O ₃ , YF ₃ and the like can be used as raw materials.

When the content of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is greater than 0%, it is an arbitrary component that can increase the refractive index of the glass.

However, since the raw materials of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component are expensive, if the content is large, the production cost will increase, and the effect of reducing the Nb ₂ O ₅ component or the WO ₃ component will be offset. . In addition, by reducing the Gd ₂ O ₃ component or the Yb ₂ O ₃ component, the increase in the Abbe number of the glass can be suppressed. Therefore, the respective contents of Gd ₂ O ₃ and Yb ₂ O ₃ are preferably less than 4.0%, preferably less than 2.0%, more preferably less than 1.0%, and still more preferably less than 0.5% , and still more preferably less than 0.1%. In particular, from the viewpoint of material cost reduction, it is preferable not to contain these components.

_Gd2O3 component and _{Yb2O3 component} , _Gd2O3 , _GdF3 , _{Yb2O3 etc. can} be _used as a raw material.

When the content of Ta ₂ O ₅ is more than 0%, the refractive index of the glass can be increased, and the devitrification resistance can be improved.

However, since the raw material of Ta ₂ O ₅ component is expensive, if the content is large, the production cost will increase, and the effect of reducing the Nb ₂ O ₅ component or the WO ₃ component will be offset. Further, by making the content of the Ta ₂ O ₅ component less than 5.0%, the melting temperature of the raw material can be lowered, and the energy required for melting the raw material can be reduced, so that the manufacturing cost of the optical glass can also be reduced. Therefore, the content of Ta ₂ O ₅ is preferably less than 5.0%, preferably less than 3.0%, more preferably less than 1.0%, still more preferably less than 0.5%, and still more preferably less than 0.1% %. In particular, from the viewpoint of material cost reduction, it is preferable not to contain a Ta ₂ O ₅ component.

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

When the content of the MgO component, the CaO component, the SrO component, and the BaO component is more than 0%, the refractive index and meltability of the glass can be improved, and the devitrification resistance can be adjusted.

Among them, by making the content of the MgO component, the CaO component, the SrO component, and the BaO component each 10.0% or less, the decrease in the refractive index can be suppressed and devitrification caused by excessive content of these components can be reduced. Therefore, the individual contents of the MgO component, the CaO component, the SrO component and the BaO component are respectively preferably 10.0% or less, preferably less than 5.0%, more preferably less than 3.0%, and still more preferably less than 1.0%.

For MgO component, CaO component, SrO component and BaO, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr(NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba(NO ₃ ) ₂ , BaF ₂ and the like can be used as raw materials .

When the content of the Li ₂ O component, the Na ₂ O component and the K ₂ O component is more than 0%, the meltability of the glass can be improved, and the arbitrary components of the glass transition point can be reduced.

On the other hand, by setting the individual contents of the Li ₂ O component, the Na ₂ O component, and the K ₂ O component to be 10.0% or less, the refractive index can be less likely to decrease, and the devitrification of the glass can be reduced. In addition, by reducing the content of the Li ₂ O component in particular, the viscosity of the glass can be increased, so that the grains of the glass can be reduced. Therefore, the individual contents of the Li ₂ O component, the Na ₂ O component and the K ₂ O component are respectively preferably 10.0% or less, preferably less than 5.0%, more preferably less than 3.0%, and still more preferably less than 1.0% %, still more preferably less than 0.5%, still more preferably less than 0.1%.

Li ₂ O component, Na ₂ O component and K ₂ O component, Li ₂ CO ₃ , LiNO ₃ , Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ and the like are used as raw materials.

When the content of P ₂ O ₅ is greater than 0%, the liquidus temperature of glass can be lowered and the devitrification resistance can be improved.

_On the other hand, by making content of a _P2O5 component 10.0% or less, it can suppress that the chemical durability of glass falls, especially the fall of water resistance. Therefore, the content of the P ₂ O ₅ component is preferably 10.0% or less, preferably less than 5.0%, more preferably less than 3.0%.

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

When the content of GeO ₂ is more than 0%, the refractive index of the glass can be increased, and the devitrification resistance can be improved.

However, since the raw material of GeO ₂ is expensive, if the content of GeO 2 is large, the production cost will increase, and the effect of reducing the Gd ₂ O ₃ component or the Ta ₂ O ₅ component will be offset. Therefore, the content of the GeO ₂ component is preferably less than 10.0%, preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably less than 0.1%. From the viewpoint of material cost reduction, the GeO ₂ component may not be contained.

For the GeO ₂ component, GeO ₂ 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 contained more than 0%, the chemical durability of the glass can be improved, and the devitrification resistance of the molten glass can be improved.

On the other hand, by setting the individual contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to be 15.0% or less, respectively, the liquidus temperature of the glass can be lowered, and the devitrification resistance can be improved. Therefore, the individual contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component are respectively preferably 15.0% or less, preferably less than 10.0%, more preferably less than 5.0%, and still more preferably less than 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 and the like can be used as raw materials.

When the content of Bi ₂ O ₃ exceeds 0%, the refractive index can be increased and the glass transition point can be lowered.

On the other hand, by making content of a Bi ₂ O ₃ component 15.0% or less, the liquidus temperature of glass can be lowered, and the devitrification resistance of glass can be improved. Therefore, the content of Bi ₂ O ₃ is preferably less than 15.0%, preferably less than 10.0%, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably less than 1.0% .

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

When the content of TeO ₂ is more than 0%, the refractive index can be increased and the glass transition point can be lowered.

On the other hand, when the glass raw material is melted by a platinum crucible or a melting tank formed of platinum at a portion in contact with the molten glass, there is a problem that the TeO ₂ component may be alloyed with platinum. Therefore, the content of the TeO ₂ component is preferably less than 15.0%, preferably less than 10.0%, more preferably less than 5.0%, still more preferably less than 3.0%, and still more preferably less than 1.0%.

For the TeO ₂ component, TeO ₂ or the like can be used as a raw material.

_SnO2 component is an arbitrary component that can reduce the oxidation of molten glass to make it clear and improve the visible light transmittance of glass when its content is greater than 0%.

On the other hand, by making content of a _SnO2 component 3.0 % or less, glass coloration by molten glass reduction, or glass devitrification can be reduced. In addition, since the alloying between the SnO ₂ composition and the melting equipment (particularly noble metals such as Pt) is reduced, the useful life of the melting equipment can be expected to be extended. Therefore, the content of the SnO ₂ component is preferably 3.0% or less, preferably less than 1.0%, more preferably less than 0.5%, and still more preferably less than 0.1%.

As the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ and the like can be used as raw materials.

The Sb ₂ O ₃ component is an arbitrary component capable of defoaming the molten glass when its content exceeds 0%.

On the other hand, when the content of the Sb ₂ O ₃ component is too large, the transmittance in the short wavelength range of the visible light range is deteriorated. Therefore, the content of the Sb ₂ O ₃ component is preferably 1.0% or less, preferably less than 0.5%, more preferably less than 0.3%.

As the Sb ₂ O ₃ component, Sb ₂ O ₃ , Sb ₂ O ₅ , Na ₂ H ₂ Sb ₂ O ₇ can be used. 5H ₂ O etc. as raw materials.

In addition, the component which makes glass clear and defoaming is not limited to the above-mentioned Sb ₂ O ₃ component, and a well-known clarifying agent, defoaming agent, or a combination thereof can be used in the field of glass production.

When the F component is more than 0%, it can increase the Abbe number of the glass, lower the glass transition point, and can improve the devitrification resistance.

However, if the content of the F component, that is, the total amount of F in the fluoride that replaces one or more of the oxides of one or two or more of the above-mentioned metal elements, is more than 15.0%, the volatilization of the F component will occur. As the amount increases, it becomes difficult to obtain stable optical constants, and it becomes difficult to obtain homogeneous glass. In addition, the Abbe number will rise above required.

Therefore, the content of the F component is preferably 15.0% or less, preferably less than 10.0%, more preferably less than 5.0%, and still more preferably less than 3.0%.

The F component can be contained in glass by using, for example, ZrF ₄ , AlF ₃ , NaF, CaF ₂ or the like as a raw material.

The ratio of the ZnO component content to the Ln ₂ O ₃ component content is preferably greater than 0 to 1.50 or less.

In particular, by making this mass ratio larger than 0, meltability can be improved, and devitrification of glass can be reduced. Therefore, the mass ratio Ln ₂ O ₃ /ZnO is preferably greater than 0, preferably 0.30 or more, more preferably 0.40 or more.

On the other hand, by making this mass ratio 1.50 or less, the fall of a refractive index can be suppressed. Therefore, the mass ratio Ln ₂ O ₃ /ZnO is preferably 1.50 or less, preferably 1.30 or less, and more preferably 1.00 or less.

The ratio of the content of the ZnO component to the content of the SiO ₂ component and the B ₂ O ₃ component is preferably greater than 0 to 2.00.

In particular, by making the mass ratio larger than 0, the meltability can be continuously improved and the refractive index can be increased. Therefore, the mass ratio ZnO/(B ₂ O ₃ +SiO ₂ ) is preferably greater than 0, preferably 0.30 or more, and more preferably 0.40 or more.

On the other hand, by making this mass ratio 2.00 or less, deterioration of devitrification property can be suppressed. Therefore, the mass ratio ZnO/(B ₂ O ₃ +SiO ₂ ) is preferably 2.00 or less, preferably 1.80 or less, and more preferably 1.50 or less.

The total amount of the B ₂ O ₃ component and the SiO ₂ component is preferably 15.0% or more and 35.0% or less.

In particular, by making the total amount 15.0% or more, deterioration of devitrification properties can be suppressed. Therefore, the mass sum (B ₂ O ₃ +SiO ₂ ) is preferably 15.0% or more, preferably 18.0% or more, more preferably 20.0% or more, and still more preferably 23.0% or more.

On the other hand, by setting the mass sum to be 35.0% or less, the decrease in the refractive index can be suppressed. Therefore, the mass sum is preferably 35.0% or less, preferably 30.0% or less, and more preferably 28.0% or less.

The total amount of the Ta ₂ O ₅ component, the Nb ₂ O ₅ component and the WO ₃ component is preferably less than 7.0%. Thereby, the content of these expensive components can be reduced, so that the material cost of glass can be reduced. Therefore, the mass sum (Ta ₂ O ₅ +Nb ₂ O ₅ +WO ₃ ) is preferably less than 7.0%, preferably less than 8.0%, more preferably less than 5.0%, and still more preferably less than 3.0% , still more preferably less than 2.0%, still more preferably less than 1.0%. In particular, from the viewpoint of obtaining glass with low material cost, it is more preferably less than 0.1%, and more preferably 0%.

The ratio of the ZnO component content to the La ₂ O ₃ component and the Y ₂ O ₃ component content is preferably 0.50 or more and 3.00 or less.

In particular, by making this ratio 0.50 or more, the meltability of the glass raw material can be improved, and more stable glass can be easily obtained. Therefore, the lower limit of the mass ratio ZnO/(La ₂ O ₃ +Y ₂ O ₃ ) is preferably 0.50 or more, preferably 0.80 or more, and more preferably 1.00 or more.

On the other hand, by making this mass ratio 3.00 or less, the liquidus temperature can be lowered, and devitrification can be reduced because the glass transition point is lowered more than necessary. Therefore, the upper limit of the mass ratio ZnO/(La ₂ O ₃ +Y ₂ O ₃ ) is preferably 3.00 or less, preferably 2.50 or less, more preferably 2.30 or less.

The total content (mass sum) of the Ln ₂ O ₃ component (Ln is at least one selected from the group consisting of La, Gd, Y, Yb, and Lu) is preferably 10.0% or more and 60.0% or less.

In particular, by setting the mass sum to be 10.0% or more, the refractive index and the Abbe number can be increased, so that the glass having the desired refractive index and the Abbe number can be easily obtained. Therefore, the mass sum of Ln ₂ O ₃ is preferably 10.0% or more, preferably more than 15.0%, more preferably more than 20.0%, still more preferably more than 25.0%, and still more preferably more than 30.0%.

On the other hand, by making this mass sum 60.0% or less, the liquidus temperature of the glass can be lowered, so that the devitrification of the glass can be reduced. In addition, the Abbe number can be suppressed from rising more than necessary. Therefore, the mass sum of the Ln ₂ O ₃ component is preferably less than 60.0%, preferably less than 50.0%, more preferably less than 45.0%, and still more preferably less than 43.0%.

The total content of RO components (R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 15.0% or less. Thereby, a decrease in the refractive index can be suppressed, and the stability of the glass can be improved. Therefore, the total of RO components is preferably 15.0% or less, preferably less than 10.0%, more preferably less than 5.0%.

The total content of the Rn ₂ O component (Rn is at least one selected from the group consisting of Li, Na, and K) is preferably 10.0% or less. Thereby, the viscosity of molten glass can be suppressed from falling, the refractive index of glass can be made less likely to fall, and devitrification of glass can be reduced. Therefore, the sum of the Rn ₂ O components is preferably less than 10.0%, preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and still more preferably less than 0.5%, Still more preferably, it is less than 0.1%.

<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 suitable to be contained will be described.

Other components may be added as needed within the range that does not impair the properties of the glass of the present invention. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, various transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, Mo, etc. When it is contained in a complex form, even a small amount of it will cause coloration of the glass, and it will have the property of absorbing light of a specific wavelength in the visible range. does not contain. Moreover, it is preferable not to contain each component of Rb and Cs from a viewpoint of suppressing glass coloration.

In addition, lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components that have a high environmental load, and are ideally not contained substantially, that is, not contained at all except for unavoidable contamination.

Furthermore, the components of Th, Cd, Tl, Os, Be, and Se have been regarded as harmful chemical substances in recent years, and their use tends to be avoided, not only in the glass manufacturing process, but also in the processing process and productization. It is necessary to take measures for environmental countermeasures until the subsequent disposal. Therefore, from the viewpoint of emphasizing the influence on the environment, it is preferable that these components are not contained substantially.

[Manufacturing method]

The optical glass of the present invention can be produced, for example, as follows. That is, as the raw material of each of the above-mentioned components, general optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, metaacid compounds, etc. are used so that each component is within a predetermined content range. The high-purity raw materials are mixed evenly, and the prepared mixture is put into a platinum crucible. According to the melting difficulty of the glass raw material, it is melted in an electric furnace at a temperature range of 1000 ° C to 1500 ° C for 1 hour to 10 hours, and stirred. After the homogenization, the temperature is lowered to an appropriate temperature, and the optical glass of the present invention is produced by casting in a mold and slowly cooling.

In this case, as the glass raw material, it is preferable to use a material with high melting property, whereby the melting can be performed in a lower temperature state or the melting can be performed in a shorter time, so that the productivity of the glass can be improved. ,reduce manufacturing cost. In addition, since the volatilization of components and the reaction with the crucible and the like are reduced, glass with less coloration can be easily obtained.

<physical properties>

The optical glass of the present invention has a high refractive index and a high Abbe number (low dispersion).

In particular, the lower limit of the refractive index (n _d ) of the optical glass of the present invention is preferably 1.70, more preferably 1.73, more preferably 1.75. The upper limit of the refractive index (n _d ) is preferably 1.90, more preferably 1.88, more preferably 1.85.

In addition, the lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 28, more preferably 30, more preferably 33, and still more preferably 35. The upper limit of the Abbe number (ν _d ) is preferably 55, preferably 50, more preferably lower than 48.

By having such a high refractive index, even when thinning of the optical element is desired, the amount of refraction of light can be increased. In addition, by having such low dispersion, when used as a single lens, the focus can be appropriately moved according to the wavelength of light. Therefore, for example, when an optical system is formed in combination with an optical element having high dispersion (low Abbe number), as a whole optical system, aberrations can be reduced, and high imaging characteristics can be expected.

In this way, the optical glass of the present invention can be effective in optical design, especially when forming an optical system, in addition to high imaging characteristics, the miniaturization of the optical system can also be expected, and the optical design can be improved. increased degrees of freedom.

The temperature coefficient (dn/dT) of the relative refractive index of the optical glass of the present invention has a high value.

More specifically, the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably +8.0×10 ^-6 ℃ ^-1 , preferably +8.5×10 ^-6 ℃ ^-1 , or higher ( positive value) value.

On the other hand, the upper limit value of the temperature coefficient of the relative refractive index of the optical glass of the present invention is preferably +16.0×10 ^-6 ℃ ^-1 , preferably +14.0×10 ^-6 ℃ ^-1 , more preferably +12.0× 10 ^-6 ℃ ^-1 , and it is possible to obtain the upper limit value or a value lower (in terms of negative values) than the upper limit value.

Among the glasses having a refractive index (n _d ) of 1.70 or more and an Abbe number (ν _d ) of 28 or more and 55 or less, a glass with a low temperature coefficient of relative refractive index is hardly known, so that it is difficult to be sensitive to changes in temperature due to changes in temperature. There are more options for correcting the resulting image out-of-focus, etc., and the correction can be completed more easily. Therefore, by setting the temperature coefficient of the relative refractive index within such a range, it is possible to contribute to the correction of image defocusing due to temperature changes.

The temperature coefficient of the relative refractive index of the optical glass of the present invention refers to the temperature coefficient of the refractive index (589.29 nm) of the optical glass in the air at the same temperature. The corresponding change (°C ^-1 ) is expressed as

The optical glass of the present invention is preferably a glass with high devitrification resistance, and more specifically, a glass with a low liquidus temperature. That is, the upper limit of the liquidus temperature of the optical glass of the present invention is preferably 1200°C, preferably 1150°C, and more preferably 1100°C. Thereby, even if the molten glass is flowed out at a low temperature, since the crystallization of the produced glass is reduced, the devitrification when the glass is formed from the molten state can be reduced, and the optical element using the glass can be reduced. Optical properties are affected. In addition, even if the melting temperature of the glass is lowered, the glass can still be formed, so that the energy consumed during the glass forming can be reduced, thereby reducing the manufacturing cost of the 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 generally approximately 800°C or higher, specifically 850°C or higher, and more specifically It is 900 degreeC or more. In addition, the "liquidus temperature" in this specification refers to placing 5 cc of a crushed glass sample in a platinum crucible in a platinum crucible with a capacity of 50 ml, and making the glass sample completely molten at 1250°C. The temperature was further lowered to a predetermined temperature and held for 1 hour, then taken out of the furnace to cool, and when the glass surface and the presence of crystals were directly observed, the liquidus temperature was expressed as the lowest temperature at which the existence of crystals could not be confirmed. Here, the predetermined temperature at the time of cooling is a temperature between 1200°C and 800°C at intervals of 10°C.

The optical glass of the present invention has high visible light transmittance, especially the transmittance of short-wavelength light in visible light, so that the coloration is less, so it is preferable.

In particular, if the optical glass of the present invention is represented by the transmittance of glass, in the case of a sample with a thickness of 10 mm, the upper limit of the wavelength (λ ₇₀ ) representing the spectral transmittance of 70% is preferably 450 nm, more preferably 430 nm , more preferably 400nm.

In addition, in the case of a sample with a thickness of 10 mm, the upper limit of the shortest wavelength (λ ₅ ) representing the spectral transmittance of 5% is preferably 400 nm, preferably 380 nm, and more preferably 360 nm.

Thereby, the absorption limit of the glass becomes near the ultraviolet region, and the transparency of the glass relative to visible light can be improved, so the optical glass can be applied to optical elements such as lenses that transmit light.

[Preform and Optical Element]

A glass compact can be produced from the optical glass produced by, for example, a method of grinding, or a method of press forming such as reheat press forming and precision press forming. That is, the glass press body can be produced in the following manner: the optical glass is subjected to mechanical processing such as grinding and grinding to produce a glass press body; a preform for press molding is produced from the optical glass, and the preform After the formed body is reheated and pressed, it is then ground to produce a glass press body; the preform produced by grinding, or the preform formed by the well-known float forming, etc., are subjected to precise processing. Press molding to produce glass compacts, etc. In addition, the method of producing a glass compact is not limited to the above-mentioned methods.

In this way, the optical glass of the present invention can function in various optical elements and optical designs. Among them, it is particularly desirable to form a preform from the optical glass of the present invention, and to use the preform to perform reheat press molding, precision press molding, or the like to produce optical elements such as lenses and lenses. As a result, a preform with a large diameter can be formed, and therefore, in addition to an increase in the size of the optical element, high-definition and high-precision imaging characteristics and projection characteristics can be realized when used in optical equipment.

The glass press body made of the optical glass of the present invention can be used in the application of optical elements such as lenses, mirrors, mirrors, etc., and most typically, it can be used in optical equipment for vehicles, projectors, photocopiers, etc., and is easy to produce. on hot machines.

[Example]

Composition of Examples (No. 1 to No. 50) of the present invention, refractive index (n _d ), Abbe number (ν _d ), temperature coefficient of relative refractive index (dn/dT), penetration of these glasses The results of the ratio (λ ₅ , λ ₇₀ ) and liquidus temperature are shown in Tables 1 to 7. In addition, the following examples are for illustrative purposes only, and the present invention is not limited to these examples.

In the glass of the embodiment of the present invention, the raw materials of each component are selected from the high-purity raw materials used in general optical glass such as oxides, hydroxides, carbonates, nitrates, fluorides, metaacid compounds, etc. The raw materials were then weighed and uniformly mixed in the composition ratios of the respective examples shown in the table, and then placed in a platinum crucible. The temperature range of 1 hour to 10 hours after melting, stirring to homogenize, and then pouring into a mold, etc., and slow cooling to produce.

The glass refractive index (n _d ) and Abbe number (ν _d ) of the examples are represented by measured values with respect to the d line (587.56 nm) of the helium lamp. In addition, Abbe's number (ν _d ) is the refractive index using the above-mentioned d line, the refractive index (n _F ) with respect to the F line (486.13 nm) of the hydrogen lamp, and the refractive index (n) with respect to the C line (656.27 nm). _c ), the Abbe number is calculated from the formula of Abbe number (ν _d )=[(n _d -1)/(n _F - n _c )]. Here, the refractive index and the Abbe number are obtained by measuring the glass obtained by setting the slow cooling rate to -25°C/hr.

The temperature coefficient of the relative refractive index (dn/dT) of the glass of the examples is based on the interference method in the method described in the Japan Optical Glass Industry Association standard JOGIS18-2008 "Measurement method of the temperature coefficient of the refractive index of optical glass". The numerical value of the temperature coefficient of the relative refractive index between 40°C and 60°C in the case of light with a wavelength of 589.29 nm.

The glass transmittance of the examples was measured according to the Japan Optical Glass Industry Association standard JOGIS02. Moreover, in this invention, by measuring the transmittance|permeability of glass, the presence or absence of coloring of glass and the degree of coloration can be known. Specifically, the spectral transmittance from 200 nm to 800 nm was measured on a surface-parallel polishing article with a thickness of 10±0.1 mm according to JISZ8722, and λ ₅ (wavelength when transmittance was 5%) and λ ₇₀ (transmittance at 5%) were obtained. wavelength at a rate of 70%).

The liquidus temperature of the glass in the examples is that in a platinum crucible with a capacity of 50ml, a 5cc shard-shaped glass sample is put into the platinum crucible, and the glass sample is completely melted at 1250°C, and then the temperature is lowered to a predetermined temperature. Hold for 1 hour; the specified temperature refers to any temperature between 1200℃ and 800℃, set every 10℃; then take it out of the furnace to cool, and directly observe the glass surface and whether there are crystals in the glass, it is impossible to find The lowest temperature at which the existence of crystals was confirmed was taken as the liquidus temperature.

As shown in the table, regardless of the optical glass of the examples, the temperature coefficient of the relative refractive index is in the range of +8.0×10(°C ^-1 ) ^-6 to +16.0×10 ^-6 (°C ^-1 ), which is within the desired range.

In addition, the refractive index (n _d ) of the optical glass of the Examples was 1.70 or more, which was within a desired range. Furthermore, the Abbe number (ν _d ) of the optical glass of the embodiment of the present invention is all within the range of 28 or more and 55 or less.

In addition, regardless of the optical glass of the examples of the present invention, its λ ₇₀ (wavelength when the transmittance is 70%) is 450 nm or less. In addition, regardless of the optical glass of the embodiment of the present invention, its λ ₅ (wavelength when the transmittance is 5%) is 400 nm or less. Therefore, it can be clearly seen that the optical glass of the embodiment of the present invention has high transmittance with respect to visible light, and is difficult to color.

Moreover, the optical glass liquidus temperature of the Example of this invention is 1200 degrees C or less. Therefore, it can be clearly seen that the optical glass of the embodiment of the present invention is a stable glass without devitrification.

Further, a glass brick was formed using the optical glass of the embodiment of the present invention, and the glass brick was ground and polished to be processed into the shape of a lens and a sapphire. As a result, it can be stably processed into various shapes of lenses and lenses.

Although the present invention has been described in detail for the purpose of illustration, the purpose of this embodiment is only for illustration, and it should be understood by those skilled in the art without departing from the spirit and scope of the present invention. Numerous modifications can be made to the present invention.

Claims (6)

An optical glass, in mass %, containing: B ₂ O ₃ composition 10.0% to 45.0%; SiO ₂ composition greater than 0% to 15.0%; ZnO composition greater than 20.0% to 60.0%; and La ₂ O ₃ composition 10.0% to 10.0% 50.0%; the temperature coefficient (40°C to 60°C) of the relative refractive index (589.29nm) of the aforementioned optical glass is in the range of +8.0×10 ^-6 (°C ^-1 ) to +16.0×10 ^-6 (°C ^-1 ) within the range. The optical glass according to claim 1, wherein the mass sum (Ta ₂ O ₅ +Nb ₂ O ₅ +WO ₃ ) is less than 7.0%. The optical glass according to claim 1 or 2, which has a refractive index (n _d ) of 1.70 or more and 1.90 or less, and has an Abbe number (ν _d ) of 28 or more and 55 or less. A preform made of the optical glass described in any one of claims 1 to 3. An optical element made of the optical glass described in any one of claims 1 to 3. An optical device provided with the optical element as described in claim 5.