TW201900572A - Optical glass, preform, and optical element having high refractive index and low dispersion optical characteristics and having a high temperature coefficient of relative refractive index - Google Patents

Abstract

An object 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 high refractive index and low dispersion optical characteristics; in addition, it has a high temperature coefficient of relative refractive index which can contribute to correction of making an impact on imaging characteristics due to temperature change. The optical glass contains, by mass%, 10.0% to 45.0% of a B2O3 component, more than 0% to 15.0% of a SiO2 component, more than 15.0% to 60.0% of a ZnO component, and 10.0% to 50.0% of a La2O3 component, and the temperature coefficient (40 DEG C to 60 DEG C) of the relative refractive index (589.29nm) is in the range between + 8.0 * 10<SP> -6</SP> (DEG C<SP> -1</SP> ) and +16.0 * 10 <SP>-6</SP> (DEG C<SP> -1</SP>).

Description

 Optical glass, preforms, and optical components  

This invention relates to optical glass, preforms, and optical components.

In recent years, optical components incorporated in automotive optical equipment such as in-vehicle cameras, or optical components incorporated in projectors, computers, laser printers, and playback equipment, which generate a large amount of heat, have been used at higher temperatures. The situation of the environment continues to increase. In such a high-temperature environment, the temperature of the optical element constituting the optical system is likely to vary greatly, and the temperature often reaches 100 ° C or higher. At this time, the negative influence on the imaging characteristics of the optical system due to the temperature fluctuation is so large that it cannot be ignored. Therefore, it is desirable to constitute an optical system which is difficult to affect the imaging characteristics and the like even if temperature fluctuation occurs.

As a material constituting the optical element of the optical system, the demand for 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 extremely high. As such a high refractive index glass, for example, a glass composition represented by Patent Documents 1 to 2 is known.

 [Previous Technical Literature]    [Patent Literature]  

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

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

In the case of an optical system that does not easily affect imaging performance due to temperature fluctuations, two types of optical elements are used in combination: an optical fiber having a lower refractive index when the temperature rises, and a glass having a negative temperature coefficient of relative refractive index An element is an optical element composed of glass having a high refractive index when the temperature is high and a temperature coefficient of a relative refractive index becomes a positive value, whereby the influence of temperature change on imaging characteristics and the like can be corrected, which 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, it is advantageous in terms of contributing to correction of influence on imaging characteristics due to temperature change. In other words, it is preferable that the temperature coefficient of the relative refractive index is large, and more specifically, it is preferable that the temperature coefficient of the relative refractive index is a positive value, or the absolute value of the temperature coefficient of the relative refractive index is large. glass.

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

In order to solve the problem, the inventors of the present invention have focused on the results of cumulative experimental 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 numerical value of the temperature coefficient of the refractive index is high, and the present invention has been completed. In particular, the invention provides the following.

(1) An optical glass containing, by mass%, 10.0% to 45.0% of a B ₂ O ₃ component, 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 the temperature coefficient of relative refractive index (589.29 nm) (40 ° C to 60 ° C) is in the range of +8.0 × 10 ^-6 (°C ^-1 ) to +16.0 × 10 ^-6 (°C ^-1 ) Inside.

(2) The optical glass of (1), wherein the mass and (Ta ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) are 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 an Abbe number (ν _d ) of 28 or more and 55 or less.

(4) A preformed body obtained from the optical glass according to any one of (1) to (3).

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

(6) An optical device comprising the optical element according to (5).

According to the present invention, it is possible to obtain an optical glass having a high refractive index and low dispersion optical property, and a value of a temperature coefficient of a relative refractive index is high, and can contribute to correcting an influence on an imaging property due to a temperature change. And using the preforms and optical elements of the optical glass.

The optical glass of the present invention contains, by mass%, 10.0% to 45.0% of the B ₂ O ₃ component, SiO ₂ component of more than 0% to 15.0%, ZnO component of more than 15.0% to 60.0%, and La ₂ O ₃ component of 10.0%. When 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 is adjusted to 50.0%, the value of the temperature coefficient of the relative refractive index is made low. Therefore, it is possible to obtain an optical glass having a high refractive index and low dispersion optical property, and a value of a temperature coefficient of a relative refractive index is high, and can contribute to the correction of the influence on the imaging characteristics due to temperature change.

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 embodiments, and can be appropriately modified and implemented within the scope of the object of the present invention. In addition, although the description of the part which repeats description is abbreviate|omitted suitably, it does not limit the summary of this invention.

 [Glass composition]  

The composition range of each component constituting the optical glass of the present invention is as follows. In the present specification, the content of each component is expressed by mass% of the total mass of the composition in terms of oxide, unless otherwise specified. Here, the "oxide-converting composition" is a case where an oxide, a composite salt, a metal fluoride or the like which is used as a raw material of the glass constituent component of the present invention is decomposed into an oxide at the time of melting, and the formation is performed. The total mass of the oxide is set to 100% by mass to represent the composition of various components contained in the glass.

<About essential ingredients, optional ingredients>

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

On the other hand, when the content of the B ₂ O ₃ component is 45.0% or less, a larger refractive index can be easily obtained, and deterioration in 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%, 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 or the like can be used as a raw material.

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

On the other hand, when the content of the SiO ₂ component is 15.0% or less, the increase in the glass transition point can be suppressed, and the decrease in the refractive index can be suppressed. Therefore, the content of the SiO ₂ component is preferably 15.0% or less, 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%, the melting property of the raw material can be improved, the defoaming of the molten glass can be promoted, and the stability of the glass can be improved, and the temperature coefficient of the relative refractive index can be increased. Furthermore, the composition also lowers the glass transition point and improves chemical durability. Therefore, the content of the ZnO component is preferably more than 15.0%, preferably more than 18.0%, more preferably more than 20.0%.

On the other hand, by setting the content of the ZnO component to 60.0% or less, it is possible to suppress the decrease in the refractive index of the glass and to reduce the devitrification caused by excessively low viscosity. Therefore, the content of the ZnO component is preferably 60.0% or less, preferably less than 50.0%, more preferably less than 45.0%, 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 of the glass and the Abbe number. Therefore, the content of the La ₂ O ₃ component is preferably 10.0% or more, more preferably 15.0% or more, still more preferably 20.0% or more, still more preferably more than 25.5%.

On the other hand, when the content of the La ₂ O ₃ component is 55.0% or less, the devitrification can be reduced by improving the stability of the glass, and the Abbe number can be prevented from rising to a required level or more. In addition, the meltability of the 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 or 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 the TiO ₂ component is more than 0%, the refractive index of the glass can be increased, and the optional component of the stability can be improved by lowering the liquidus temperature of the glass. Therefore, the content of the TiO ₂ component is preferably more than 0%, preferably more than 1.0%, more preferably more than 3.0%.

On the other hand, when the content of the TiO ₂ component is 15.0% or less, devitrification due to an excessive content of the TiO ₂ component can be reduced, and the transmittance of the glass with respect to visible light (especially, a wavelength of 500 nm or less) can be suppressed from being lowered. . In addition, it is possible to suppress the decrease in the Abbe number. Therefore, the content of the TiO ₂ component is preferably 15.0% or less, preferably 13.0% or less, more preferably less than 10.0%.

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

When the content of the ZrO ₂ component is more than 0%, the refractive index and the Abbe number of the glass can be increased, and any component which is resistant to devitrification can be improved. Therefore, the content of the ZrO ₂ component is preferably more than 0%, preferably more than 1.0%, more preferably more than 2.0%.

On the other hand, by setting the content of the ZrO ₂ component to 10.0% or less, devitrification caused by an excessive content of the ZrO ₂ component can be reduced. Therefore, the content of the ZrO ₂ component is preferably 10.0% or less, preferably less than 8.0%, more preferably less than 5.0%.

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

When the content of the Nb ₂ O ₅ component is more than 0%, the refractive index of the glass can be increased, and the component which is resistant to devitrification can be improved by lowering the liquidus temperature of the glass.

On the other hand, by setting the content of the Nb ₂ O ₅ component to less than 10.0%, the material cost of the glass can be lowered. Further, it is possible to reduce devitrification caused by an excessive content of the Nb ₂ O ₅ component, and it is possible to suppress a decrease in the transmittance of the glass with respect to visible light (especially, a wavelength of 500 nm or less). In addition, it is possible to suppress the Abbe number from being lowered. Therefore, the content of the Nb ₂ O ₅ 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 further preferably less than 0.1%. In particular, from the viewpoint of reducing the material cost, it is preferable that the Nb ₂ O ₅ component is not contained.

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

When the content of the WO ₃ component is more than 0%, in addition to reducing the coloration of the glass by other high refractive index components, the refractive index can be increased, the glass transition point can be lowered, and any component which is resistant to devitrification can be improved.

On the other hand, by setting the content of the WO ₃ component to less than 10.0%, the material cost of the glass can be lowered. In addition, the glass coloration caused by the WO ₃ component can be reduced, and the 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 even more preferably less than 0.5%. More preferably, it is less than 0.1%. In particular, from the viewpoint of reducing the material cost, it is preferable that the WO ₃ component is not contained.

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

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

On the other hand, by setting the content of the Y ₂ O ₃ component to 20.0% or less, the refractive index of the glass can be suppressed from being lowered, and the stability of the glass can be improved. Further, it is possible to suppress the deterioration of the meltability of the glass raw material. Therefore, the content of the Y ₂ O ₃ component is preferably 20% or less, preferably less than 18.0%, more preferably less than 15.0%, still more preferably less than 13.0%.

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

When the content of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is more than 0%, an arbitrary component which can increase the refractive index of the glass can be obtained.

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 high, the production cost becomes high, and the effect of reducing the Nb ₂ O ₅ component or the WO ₃ component is offset. . Further, 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 individual content of the Gd ₂ O ₃ component and the Yb ₂ O ₃ component is preferably less than 4.0%, preferably less than 2.0%, more preferably less than 1.0%, and even more preferably less than 0.5%. More preferably, it is less than 0.1%. In particular, from the viewpoint of reducing the material cost, it is preferable that the components are not contained.

As the Gd ₂ O ₃ component and the Yb ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ , Yb ₂ O ₃ or the like can be used as a raw material.

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

However, since the raw material of the Ta ₂ O ₅ component is expensive, if the content is high, the production cost becomes high, and the effect by reducing the Nb ₂ O ₅ component or the WO ₃ component is offset. Further, by setting the content of the Ta ₂ O ₅ component to 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 production cost of the optical glass can be reduced. Therefore, the content of the Ta ₂ O ₅ component 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 reducing the material cost, it is preferable that the Ta ₂ O ₅ component is not contained.

As 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 or the meltability of the glass can be improved, and an optional component which is resistant to devitrification can be adjusted.

In the case where the content of the MgO component, the CaO component, the SrO component, and the BaO component is 10.0% or less, it is possible to suppress the decrease in the refractive index and to reduce the devitrification caused by the excessive content of the components. Therefore, the individual content of the MgO component, the CaO component, the SrO component, and the BaO component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.

As the raw material of 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 or the like can be used. .

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 optional component of the glass transition point can be lowered.

On the other hand, by setting the individual content of the Li ₂ O component, the Na ₂ O component, and the K ₂ O component to 10.0% or less, the refractive index is not easily lowered, and the devitrification of the glass can be reduced. Further, in particular, by reducing the content of the Li ₂ O component, the viscosity of the glass can be improved, so that the grain 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 preferably 10.0% or less, preferably less than 5.0%, more preferably less than 3.0%, and still more preferably less than 1.0. %, and further preferably less than 0.5%, and even more preferably less than 0.1%.

As the Li ₂ O component, the Na ₂ O component, and the 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, or the like can be used. KHF ₂ , K ₂ SiF ₆ and the like are used as raw materials.

When the content of the P ₂ O ₅ component is more than 0%, the liquidus temperature of the glass can be lowered, and any component which is resistant to devitrification can be improved.

On the other hand, by setting the content of the P ₂ O ₅ component to 10.0% or less, it is possible to suppress the chemical durability of the glass from being lowered, and in particular, the water resistance is lowered. Therefore, the content of the P ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%.

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 content of the GeO ₂ component is more than 0%, the refractive index of the glass can be increased, and any component which is resistant to devitrification can be improved.

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

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

When the content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is 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, when the respective contents of the Al ₂ O ₃ component and the Ga ₂ O ₃ component are each 15.0% or less, the liquidus temperature of the glass can be lowered, and the devitrification resistance can be improved. Therefore, the individual content of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0% or less, preferably less than 10.0%, more preferably less than 5.0%, still more preferably less than 3.0%.

As the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al(OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga(OH) ₃ or the like can be used as a raw material.

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

On the other hand, by setting the content of the Bi ₂ O ₃ component to 15.0% or less, the liquidus temperature of the glass can be lowered, and the devitrification resistance of the glass can be improved. Therefore, the content of the Bi ₂ O ₃ component is preferably 15.0% or less, 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%. .

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

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

On the other hand, when the glass raw material is melted by a crucible made of platinum or a molten bath formed by platinum in 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 15.0% or less, 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%.

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

When the content of the SnO ₂ component is more than 0%, it is possible to reduce the oxidation of the molten glass to make it clear, and to increase the visible light transmittance of the glass.

On the other hand, by setting the content of the SnO ₂ component to 3.0% or less, it is possible to reduce glass coloration or devitrification of the glass due to reduction of molten glass. Further, since the alloying between the SnO ₂ component and the melting device (particularly, a noble metal such as Pt) is reduced, it is expected that the life of the melting device is prolonged. 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%, still more preferably less than 0.1%.

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

The Sb ₂ O ₃ component is an optional component which can defoam the molten glass when the content thereof is more than 0%.

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

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

When the content of the F component is more than 0%, the Abbe number of the glass can be increased, the glass transition point can be lowered, and any component which is resistant to devitrification can be improved.

However, the content of the F component, that is, the total amount of F of the fluoride in which one or both of the oxides of one or more of the above metal elements are substituted, and if it is more than 15.0%, the v component is volatilized. Since the amount becomes large, it becomes difficult to obtain a stable optical constant, and it is not easy to obtain a homogeneous glass. In addition, the Abbe number will rise above the required level.

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

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

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

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

On the other hand, by setting the mass ratio to 1.50 or less, the decrease in the 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, 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 more than 0 or more and 2.00 or less.

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

On the other hand, by setting the mass ratio to 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, 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 setting the total amount to 15.0% or more, deterioration of devitrification property can be suppressed. Therefore, the mass and (B ₂ O ₃ + SiO ₂ ) are preferably 15.0% or more, more preferably 18.0% or more, still more preferably 20.0% or more, and still more preferably 23.0% or more.

On the other hand, by setting the mass sum to 35.0% or less, the decrease in the refractive index can be suppressed. Therefore, the mass is preferably 35.0% or less, preferably 30.0% or less, 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 high-priced components can be reduced, so that the material cost of the glass can be reduced. Therefore, the mass and (Ta ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) are preferably less than 7.0%, preferably less than 8.0%, more preferably less than 5.0%, and even more preferably less than 3.0%. Further preferably, it is less than 2.0%, and even more preferably less than 1.0%. In particular, from the viewpoint of obtaining a glass having a low material cost, it is more preferably less than 0.1%, and most preferably 0%.

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

In particular, by setting the ratio to 0.50 or more, the meltability of the glass raw material can be improved, and a 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, more preferably 0.80 or more, still more preferably 1.00 or more.

On the other hand, by setting the mass ratio to 3.00 or less, the liquidus temperature can be lowered, and devitrification can be reduced, which is caused by the glass transition point being lowered to 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, more preferably 2.50 or less, still more preferably 2.30 or less.

The sum (mass sum) of the content of the Ln ₂ O ₃ component (Ln is one or more 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 10.0% or more, the refractive index and the Abbe number can be increased, and therefore, a glass having a desired refractive index and Abbe number can be easily obtained. Accordingly, the mass of the Ln ₂ O ₃ component is preferably 10.0% or more, more preferably more than 15.0%, still 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 setting the mass sum to 60.0% or less, the liquidus temperature of the glass can be lowered, so that devitrification of the glass can be reduced. In addition, it is possible to suppress the Abbe number from rising above the required level. Therefore, the mass of the Ln ₂ O ₃ component is preferably 60.0% or less, preferably less than 50.0%, more preferably less than 45.0%, still more preferably less than 43.0%.

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

The sum of the content of the Rn ₂ O component (Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 10.0% or less. Thereby, the viscosity of the molten glass can be suppressed from being lowered, the refractive index of the glass is not easily lowered, and the devitrification of the glass can be reduced. Therefore, the sum of the Rn ₂ O components is preferably 10.0% or less, 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%. Further preferably, it is less than 0.1%.

<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 suitable for inclusion will be described.

Other components may be added as needed within the range not impairing the characteristics of the glass of the present invention. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, various transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo are individually or When the composite type is contained, even if it is contained in a small amount, the glass is colored, and there is a property of absorbing light of a specific wavelength in the visible range. Therefore, especially in an optical glass using a wavelength of a visible range, it is preferably Does not contain. Further, it is preferable that each component of Rb and Cs is not contained from the viewpoint of suppressing coloration of the glass.

Further, a lead compound such as PbO or an arsenic compound such as As ₂ O ₃ is preferably a component which is high in environmental load, and is preferably substantially not contained, that is, it is not contained at all except for inevitable mixing.

Further, various components of Th, Cd, Tl, Os, Be, and Se have been regarded as harmful chemical substances in recent years, and there is a tendency to avoid use, not only in the manufacturing steps of glass, but also in processing steps and productization. In the case of disposal after the disposal, measures must be taken in response to environmental measures. Therefore, from the viewpoint of attaching importance to environmental influences, it is preferred that substantially no such components are contained.

 [Production method]  

The optical glass of the present invention can be produced, for example, in the following manner. In other words, as a raw material of each of the above components, a general optical glass such as an oxide, a hydroxide, a carbonate, a nitrate, a fluoride or a bismuth acid compound is used in such a manner that each component is within a predetermined content range. The high-purity raw materials are uniformly mixed, and the prepared mixture is placed in a platinum crucible, and melted for 1 hour to 10 hours in an electric furnace at a temperature ranging from 1000 ° C to 1500 ° C according to the ease of melting of the glass raw material, and stirred. After homogenization, the temperature was lowered to an appropriate temperature, and then cast in a mold to be slowly cooled, whereby the optical glass of the present invention was produced.

In this case, it is preferable to use a material having a high meltability as a glass raw material, whereby melting can be performed at a lower temperature, or melting can be performed in a shorter period of time, so that productivity of glass can be improved. ,reduce manufacturing cost. Further, since the volatilization of the component or the reaction with hydrazine or the like is reduced, the glass having less coloration can be easily obtained.

<physical property>

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, preferably 1.73, more preferably 1.75. The upper limit of the refractive index (n _d ) is preferably 1.90, preferably 1.88, more preferably 1.85.

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

By having such a high refractive index, the amount of light refraction can be made large even in the case where the optical element is desired to be thinned. Further, by having such low dispersion, when used as a single lens, the focus can be appropriately moved by the wavelength of light. Therefore, for example, when an optical system is constructed in combination with an optical element having a high dispersion (low Abbe number), as the entire optical system, aberration can be reduced, and high imaging characteristics and the like can be expected.

In this way, the optical glass of the present invention can exert an effect on optical design, and in particular, in the case of constituting an optical system, in addition to high imaging characteristics and the like, it is also desired to miniaturize the optical system, and optical design can be made. The degree of freedom increases.

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 ° C ^-1 , preferably +8.5 × 10 ^-6 ° C ^-1 , or can be obtained higher ( Positive value).

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

In a 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, a glass having a low temperature coefficient of relative refractive index is hardly known, so that it is caused by temperature change. There are many choices for correcting the situation such as image defocusing, and the correction can be completed more easily. Therefore, by setting the temperature coefficient of the relative refractive index to such a range, it is possible to contribute to correction of image defocusing or the like due to temperature change.

The temperature coefficient of the relative refractive index of the optical glass of the present invention means the temperature coefficient of the refractive index (589.29 nm) in the air at the same temperature as the optical glass, which is 1 ° C when the temperature is changed from 40 ° C to 60 ° C. Corresponding change amount (°C ^-1 )

The optical glass of the present invention is preferably a glass having high devitrification resistance, and more specifically, a glass having 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, more preferably 1100 ° C. Thereby, even if the molten glass flows out at a relatively low temperature, since the crystallization of the produced glass is reduced, the devitrification when the glass is formed in a molten state can be reduced, and the optical element for using the glass can be reduced. Optical properties have an impact. Further, even if the melting temperature of the glass is lowered, the glass can be formed, so that the energy consumed in forming the glass 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 glass obtained by the present invention has a liquidus temperature of about 800 ° C or more, specifically 850 ° C or more, more specifically. In terms of 900 ° C or more. In addition, the "liquidus temperature" in the present specification means that 5 cc of a crumb-like glass sample is placed in a platinum crucible in a platinum crucible having a capacity of 50 ml, and the glass sample is completely molten at 1250 ° C. Further, the temperature was lowered to a predetermined temperature for 1 hour, and then taken out to the outside of the furnace for cooling. When the surface of the glass and the presence or absence of crystals in the glass were directly observed, the liquidus temperature was indicated at the lowest temperature at which crystals could not be confirmed. Here, the predetermined temperature at the time of cooling means a temperature at intervals of 10 ° C between 1200 ° C and 800 ° C.

The optical glass of the present invention has a high visible light transmittance, and particularly has a high light transmittance in terms of a short wavelength in visible light, and therefore is preferable because it has a small coloring.

In particular, when the optical glass of the present invention is expressed by the transmittance of glass, in the case of a sample having a thickness of 10 mm, the upper limit of the wavelength (λ ₇₀ ) indicating that the spectral transmittance is 70% is preferably 450 nm, preferably 430 nm. More preferably, it is 400 nm.

Further, in the case of the optical glass of the present invention in the case of a sample having a thickness of 10 mm, the upper limit of the shortest wavelength (λ ₅ ) indicating a spectral transmittance of 5% is preferably 400 nm, preferably 380 nm, more preferably 360 nm.

Thereby, the absorption limit of the glass becomes near the ultraviolet light region, and the transparency of the glass with respect to visible light can be improved, so that the optical glass can be applied to an optical element such as a lens that penetrates light.

 [Preformed body and optical components]  

The glass compact can be produced from the produced optical glass by, for example, a method of polishing or a method of press molding such as re-press molding or precision press molding. In other words, a glass compact can be produced by mechanical processing such as grinding and polishing of an optical glass to produce a glass compact, and a preform for press molding can be produced from the optical glass, and the preform can be prepared. After the formed body is subjected to reheat press forming, polishing is performed to produce a glass compact, and a preform formed by polishing or a preform formed by known floating molding or the like is precision-finished. Press forming to produce a glass compact or the like. Further, the method of producing the glass compact is not limited to the above methods.

In this way, the optical glass of the present invention can function in a wide variety of optical components and optical designs. Among them, it is particularly preferable to form a preform by the optical glass of the present invention, and to perform reheat press molding or precision press molding using the preform, thereby producing an optical element such as a lens or a crucible. As a result, a preform having a large diameter can be formed. Therefore, in addition to an increase in the size of the optical element, it is possible to realize high-definition and high-precision imaging characteristics and projection characteristics when used on an optical device.

The glass compact obtained from the optical glass of the present invention can be used for applications such as lenses, iridium, mirrors, and the like, and most typically can be used in automotive optical equipment, projectors, photocopiers, etc., and is easy to produce. On a high temperature machine.

 [Examples]  

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

In the glass of the embodiment of the present invention, the raw materials of the respective components are selected from the high-purity raw materials used for general optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, and bismuth-acid compounds. These raw materials were weighed and uniformly mixed in the composition ratios of the respective examples shown in the table, and then placed in a platinum crucible, and in an electric furnace at 1100 ° C to 1500 ° C according to the ease of melting of the glass raw materials. After the temperature range is melted for 1 hour to 10 hours, the mixture is homogenized by stirring, cast into a mold or the like, and slowly cooled to prepare.

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

The temperature coefficient (dn/dT) of the relative refractive index of the glass of the example is an interference method according to the method described in the Japanese Optical Glass Industry Association specification JOGIS18-2008 "Method for Measuring the Temperature Coefficient of the Refractive Index of Optical Glass". The value of the temperature coefficient of the relative refractive index of 40 ° C to 60 ° C in the case of light having a wavelength of 589.29 nm.

The glass transmittance of the examples was measured in accordance with the Japan Optical Glass Industry Association specification JOGIS02. Further, in the present invention, by measuring the transmittance of the glass, it is possible to know whether or not the glass is colored or not. Specifically, a split parallel polishing product having a thickness of 10 ± 0.1 mm is used to measure a spectral transmittance of 200 nm to 800 nm according to JIS Z8722, and λ ₅ (wavelength at a transmittance of 5%) and λ ₇₀ (penetration) are obtained. The wavelength is 70%).

The glass liquidus temperature of the example is a platinum crucible having a capacity of 50 ml, and 5 cc of a crumb-like glass sample is placed in a platinum crucible, and the glass sample is completely melted at 1250 ° C, and then cooled to a predetermined temperature. Hold for 1 hour; the specified temperature refers to any temperature set between 10 ° C and 1200 ° C to 800 ° C; then, after taking out to the outside of the furnace for cooling, directly observe the presence or absence of crystals in the glass surface and the glass, The lowest temperature at which crystallization is present is confirmed as the liquidus temperature.

As shown in the table, the temperature coefficient of the relative refractive index of the optical glass of the embodiment is in the range of +8.0×10 (°C ^-1 ) ^-6 to +16.0×10 ^-6 (°C ^-1 ). Within the expected range.

Further, the optical glass of the examples had a refractive index (n _d ) of 1.70 or more, which is within a desired range. Furthermore, the optical glass of the embodiment of the present invention has an Abbe number (ν _d ) in the range of 28 or more and 55 or less.

Further, in any case of the optical glass of the embodiment of the present invention, λ ₇₀ (wavelength at a transmittance of 70%) is 450 nm or less. Further, in any case of the optical glass of the embodiment of the present invention, λ ₅ (wavelength at a transmittance of 5%) is 400 nm or less. Therefore, it is clear that the optical glass of the embodiment of the present invention has a high transmittance with respect to visible light and is difficult to color.

Further, the liquid glass liquid temperature of the embodiment of the present invention is 1200 ° C or lower. Therefore, it is clear that the optical glass of the embodiment of the present invention is a glass which is not devitrified and stabilized.

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

The present invention has been described in detail above with reference to the embodiments of the present invention, which is intended to be construed as illustrative only Many variations of the invention are possible.

Claims (6)

An optical glass containing, by mass%, 10.0% to 45.0% of a B ₂ O ₃ component; SiO ₂ component of greater than 0% to 15.0%; a ZnO component of greater than 15.0% to 60.0%; and a La ₂ O ₃ component of 10.0% to 50.0%; the relative refractive index (589.29 nm) of the optical glass has a temperature coefficient (40 ° C to 60 ° C) of +8.0×10 ^-6 (° C ^-1 ) to +16.0×10 ^-6 (°C ^-1 ). Within the scope. The optical glass of claim 1, wherein the mass and (Ta ₂ O ₅ + Nb ₂ O ₅ + WO ₃ ) are 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 an Abbe number (ν _d ) of 28 or more and 55 or less.  A preformed body obtained by the optical glass described in any one of claims 1 to 3.    An optical element comprising the optical glass described in any one of claims 1 to 3.    An optical device comprising the optical element according to claim 5.