TWI612019B - Optical glass, preforms and optical components - Google Patents

Abstract

The present invention provides an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range more inexpensively and having high transparency to visible light. The optical glass of the present invention contains 5.0% to 40.0% of a B ₂ O ₃ component, 10.0% to 40.0% of a La ₂ O ₃ component, and 10.0% with respect to the total mass of the glass in terms of oxide conversion composition. ~ 40.0% ZnO component, has a refractive index (n _d ) of 1.75 or more, and an Abbe number (ν _d ) of 30 or more and 40 or less.

Description

Optical glass, preform and optical element

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

In recent years, the digitization or high-definition of equipment using optical systems has developed rapidly, and has been reduced in the fields of photographic equipment such as digital cameras and video cameras, and various optical equipment such as image playback (projection) equipment such as projectors and projection televisions. The number of lenses or optical elements used in the optical system makes the overall optical system lighter and smaller.

In the optical glass used for the manufacture of optical elements, in particular, it has a high refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 30 or more and 40 that can achieve the weight and size reduction of the entire optical system. The need for low rate dispersion glass is very high. As such a high-refractive-index low-dispersion glass, the glass composition represented by patent documents 1-3 is known.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 48-059116

[Patent Document 2] Japanese Patent Laid-Open No. 52-103412

[Patent Document 3] Japanese Patent Laid-Open No. 2004-161506

In order to reduce the material cost of optical glass, it is desirable that the raw material of optical glass is as cheap as possible. However, the glass compositions described in Patent Documents 1 to 3 contain a large amount of rare-earth components such as Ta ₂ O ₅ component or Nb ₂ O ₅ component, and Gd ₂ O ₃ component or Yb ₂ O ₃ component because of a large amount of raw materials. Therefore, it cannot be said that the above requirements are fully met.

It is also considered that relatively inexpensive high refractive index components such as TiO ₂ components are substituted for these expensive components to obtain desired optical properties such as refractive index. However, many glasses containing such inexpensive high-refractive-index components tend to be colored, and are not suitable for the use of optical elements such as lenses or chirps that transmit visible light.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to obtain an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within a desired range and suitable for an optical element that transmits visible light at a lower cost.

The present inventors repeatedly conducted intensive experimental research to solve the above-mentioned problems, and found that by containing 10.0% or more of ZnO components relative to glass containing B ₂ O ₃ components and La ₂ O ₃ components, relatively inexpensive ZnO can be used The composition reduces the material cost of the glass, maintains the desired refractive index and Abbe number, and reduces the coloration of the glass, thereby completing the present invention. Specifically, the present invention provides the following.

(1) An optical glass containing 5.0 to 40.0% of a B ₂ O ₃ component, 10.0 to 40.0% of a La ₂ O ₃ component, and 10.0 to 40.0% with respect to the total mass of the glass in terms of oxide conversion composition. The ZnO component has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 30 or more and 40 or less.

(2) The optical glass as described in (1) above, wherein the total mass of the glass relative to the oxide conversion composition is calculated as mass%: Gd ₂ O ₃ component 0 to 5.0% Y ₂ O ₃ component 0 to 5.0% Yb ₂ O ₃ component 0 to 5.0% Lu ₂ O ₃ component 0 to 5.0% Ta ₂ O ₅ component 0 to 15.0%.

(3) The optical glass according to (1) or (2) above, wherein the mass and (Gd ₂ O ₃ + Y ₂ O ₃ + Yb ₂ O ₃ + Lu ₂ O ₃ + Ta ₂ O ₅ ) are converted with respect to the oxide The total glass mass of the composition is 15.0% or less.

(4) The optical glass according to any one of (1) to (3) above, wherein the content of the Nb ₂ O ₅ component is 20.0% or less with respect to the total mass of the glass in terms of the oxide conversion composition.

(5) The optical glass according to any one of (1) to (4) above, wherein the Ln ₂ O ₃ component (wherein, Ln is one selected from the group consisting of La, Gd, Y, Yb, and Lu The mass of the glass) and the total mass of the glass relative to the oxide conversion composition are 10.0% or more and 40.0% or less.

(6) The optical glass according to any one of the above (1) to (5), wherein the mass ratio ZnO / (Ln ₂ O ₃ + Ta ₂ O ₅ + Nb ₂ O ₅ ) of the oxide conversion composition is 0.31 or more.

(7) The optical glass according to any one of the above (1) to (6), wherein the total mass of the glass in terms of oxide conversion composition is expressed as mass%: TiO ₂ component 0 to 20.0% WO ₃ component 0 to 25.0%.

(8) The optical glass according to any one of (1) to (7) above, wherein the mass and (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) with respect to the total glass mass of the oxide-equivalent composition are 20.0% or less.

(9) The optical glass according to any one of (1) to (8) above, wherein the mass ratio of the oxide conversion composition TiO ₂ / (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 0.50 or less.

(10) The optical glass according to any one of the above (1) to (9), wherein the mass ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ of the oxide conversion composition is 0.16 or more.

(11) The optical glass according to any one of (1) to (10) above, wherein the content of the SiO ₂ component is 15.0% or less with respect to the total mass of the glass in terms of the oxide conversion composition.

(12) The optical glass according to any one of the above (1) to (11), wherein a mass ratio of the oxide-equivalent composition of SiO ₂ / B ₂ O _{3 is} less than 1.00.

(13) The optical glass according to any one of (1) to (12) above, wherein the content of the Li ₂ O component is 5.0% or less with respect to the total mass of the glass in terms of the oxide conversion composition.

(14) The optical glass according to any one of the above (1) to (13), wherein the total mass of the glass in terms of oxide conversion composition is expressed in mass% as: MgO component 0 to 10.0% CaO composition 0 ~ 10.0% SrO composition 0 ~ 10.0% BaO composition 0 ~ 10.0%.

(15) The optical glass according to any one of (1) to (14) above, wherein the mass of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) The total mass of the glass relative to the oxide conversion composition is less than 15.0%.

(16) The optical glass according to any one of (1) to (15) above, wherein the total mass of the glass in terms of the oxide conversion composition is expressed as mass%: Na ₂ O component 0 to 5.0% K ₂ O component 0 ~ 5.0% Cs ₂ O composition 0 ~ 5.0%.

(17) The optical glass according to any one of (1) to (16) above, wherein the Rn ₂ O component (where Rn is one or more selected from the group consisting of Li, Na, K, and Cs) The mass and the total mass of the glass relative to the oxide conversion composition are 10.0% or less.

(18) The optical glass according to any one of (1) to (17) above, wherein the total mass of the glass in terms of oxide conversion composition is expressed as mass%: P ₂ O ₅ component 0 to 10.0% GeO ₂ component 0 ~ 10.0% Bi ₂ O ₃ component 0 ~ 10.0% ZrO ₂ component 0 ~ 15.0% Al ₂ O ₃ component 0 ~ 5.0% Ga ₂ O ₃ component 0 ~ 5.0% TeO ₂ component 0 ~ 15.0% SnO ₂ component 0 ~ 1.0% Sb ₂ O ₃ composition 0 ~ 1.0%.

(19) An optical element comprising the optical glass according to any one of (1) to (18) above.

(20) A preform for precision press molding, comprising the optical glass according to any one of (1) to (18) above.

(21) An optical element obtained by precision press-molding a preform for precision press-molding as described in (20).

(22) A method for producing a glass formed body, which is as described in (1) to The optical glass of any one of (18) is softened and press-molded in a mold.

According to the present invention, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range and suitable for an optical element that transmits visible light can be obtained more inexpensively.

The optical glass of the present invention contains 5.0 to 40.0% of B ₂ O ₃ component, 10.0 to 40.0% of La ₂ O ₃ component, and 10.0 to 40.0% of ZnO with respect to the total mass of the glass in terms of oxide conversion composition. The component has a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 30 or more and 40 or less. By containing a ZnO component of 10.0% or more relative to a glass containing a B ₂ O ₃ component and a La ₂ O ₃ component, a relatively inexpensive ZnO component can be used to reduce the material cost of the glass while maintaining the desired refractive index and hardness. It reduces the coloration of the glass and improves the visible light transmittance. At the same time, by using a B ₂ O ₃ component and a La ₂ O ₃ component as a substrate, it is easier to obtain a refractive index (n _d ) of 1.75 or more and an Abbe number (ν _d ) of 30 or more, and coloring is performed. Fewer glasses with higher visible light transmission. Therefore, it is possible to more inexpensively obtain an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) in a desired range and suitable for an optical element that transmits visible light.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail. The present invention is not limited in any way by the following embodiments, and can be appropriately modified and implemented within the scope of the object of the present invention. In addition, the overlapping description may be omitted as appropriate, but the gist of the invention is not limited.

[Glass composition]

Hereinafter, the composition range of each component which comprises the optical glass of this invention is demonstrated. In this specification, when there is no particular limitation, the content of each component is expressed as a mass% of an oxide conversion composition with respect to the total mass of glass. Here, the "oxide conversion composition" refers to a case where the oxide, the composite salt, and the metal fluoride which are assumed to be used as the raw material of the glass constituents of the present invention are all decomposed to become oxides when melted. The total mass of the produced oxide was 100% by mass, and a composition obtained by marking each component contained in the glass.

<About essential ingredients and optional ingredients>

The B ₂ O ₃ component is a glass-forming component and is a necessary component in the optical glass of the present invention.

In particular, by containing a B ₂ O ₃ component of 5.0% or more, the formation of stable glass can be promoted, devitrification can be reduced, and the thermal stability of the glass can be improved. Therefore, the lower limit of the content of the B ₂ O ₃ component is preferably 5.0%, more preferably 6.0%, still more preferably 7.0%, and even more preferably 9.0%. In addition, the content of the B ₂ O ₃ component may be set to 15.0% or more, and may also exceed 17.0%.

On the other hand, by reducing the content of the B ₂ O ₃ component to 40.0% or less, it is possible to suppress a decrease in the refractive index of the glass and suppress a deterioration in chemical durability. Therefore, the upper limit of the content of the B ₂ O ₃ component is preferably 40.0%, more preferably 30.0%, and still more preferably 25.0%.

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

The La ₂ O ₃ component is a component that increases the refractive index and Abbe number of glass by containing 10.0% or more. In addition, it is relatively inexpensive among rare earth elements and is a component that effectively suppresses an increase in the material cost of glass. Therefore, the La ₂ O ₃ component is a component to be included in the optical glass of the present invention. Therefore, the lower limit of the content of the La ₂ O ₃ component is preferably 10.0%, more preferably 15.0%, still more preferably 17.0%, still more preferably 20.0%, and still more preferably 25.0%.

On the other hand, devitrification of glass can be reduced by setting the content of the La ₂ O ₃ component to 40.0% or less. Therefore, the upper limit of the content of the La ₂ O ₃ component is preferably 40.0%, more preferably 38.0%, and still more preferably 36.0%.

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

The ZnO component is a component within the range of the refractive index and Abbe number of the present invention, and even if it contains 10.0% or more, it has a small effect on the refractive index and Abbe number. Therefore, the inventors of the present case found that by containing a ZnO component of 10.0% or more, the desired refractive index and Abbe number can be maintained, and the material cost of glass can be reduced, and devitrification of glass can be reduced. That is, the ZnO component is a component to be contained in the optical glass of the present invention. In addition, the ZnO component is a component that improves the melting property of the glass and also reduces the manufacturing cost of the glass. Therefore, the lower limit of the content of the ZnO component is preferably 10.0%, more preferably more than 15.0%, still more preferably 16.5%, and even more preferably more than 20.0%.

On the other hand, when the content of the ZnO component is 40.0% or less, devitrification caused by excessively containing the ZnO component can be suppressed. In addition, by suppressing a decrease in the viscosity of the molten glass, the occurrence of streaks in the glass can be reduced. Therefore, the upper limit of the content of the ZnO component is preferably 40.0%, more preferably 35.0%, and further It is preferably 32.0%.

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

Gd ₂ O ₃ component, Y ₂ O ₃ component, Yb ₂ O ₃ and Lu ₂ O ₃ component are arbitrary components that increase the refractive index and Abbe number of glass and reduce devitrification when the content exceeds 0%.

On the other hand, by setting the content of each of these components to 5.0% or less, the use of these expensive components can be reduced, and the material cost of glass can be reduced. In addition, it is possible to suppress an increase in the Abbe number of the glass caused by excessively containing these components or devitrification. Therefore, the upper limit of the content of each of these components is preferably 5.0%, more preferably less than 3.0%, even more preferably less than 1.6%, still more preferably less than 0.5%, and more preferably Preferably, it is set to less than 0.3%.

Gd ₂ O ₃ component, Y ₂ O ₃ component, Yb ₂ O ₃ and Lu ₂ O ₃ component can use Gd ₂ O ₃ , GdF ₃ , Y ₂ O ₃ , YF ₃ , Yb ₂ O ₃ , Lu ₂ O _3, etc. It is contained in glass as a raw material.

When the content of Ta ₂ O ₅ is more than 0%, it is an arbitrary component that increases the refractive index of glass and reduces devitrification.

On the other hand, by setting the content of the Ta ₂ O ₅ component to 15.0% or less, the use of expensive Ta ₂ O ₅ components can be reduced, and thus the material cost of glass can be reduced. In addition, by reducing the use of the Ta ₂ O ₅ component, the melting temperature of the raw material is reduced, and the energy required for the melting of the raw material is reduced. Therefore, the manufacturing cost of the optical glass can also be reduced. Therefore, the upper limit of the content of the Ta ₂ O ₅ component is preferably 15.0%, more preferably 10.0%, still more preferably 5.0%, further preferably less than 2.0%, and even more preferably less than 1.0. %.

The Ta ₂ O ₅ component can be contained in glass using Ta ₂ O ₅ or the like as a raw material.

The total amount of the Gd ₂ O ₃ component, Y ₂ O ₃ component, Yb ₂ O ₃ component, Lu ₂ O ₃ component, and Ta ₂ O ₅ component in the optical glass of the present invention is preferably 15.0% or less. In this way, the desired refractive index and Abbe number can be maintained, and the use of these expensive components can be reduced, so the material cost of glass can be reduced. Therefore, the upper limit of the mass and (Gd ₂ O ₃ + Y ₂ O ₃ + Yb ₂ O ₃ + Lu ₂ O ₃ + Ta ₂ O ₅ ) is preferably 15.0%, more preferably less than 7.0%, and more than Preferably, it is set to less than 2.0%.

When the content of Nb ₂ O ₅ is more than 0%, it can increase the refractive index of glass, reduce devitrification, and adjust the Abbe number to any lower component. Therefore, the content of the Nb ₂ O ₅ component may be preferably set to exceed 0%, more preferably set to exceed 0.5%, and still more preferably set to exceed 1.0%.

On the other hand, by setting the content of the Nb ₂ O ₅ component to 20.0% or less, the use of expensive Nb ₂ O ₅ components can be reduced, and therefore the material cost of glass can be reduced. In addition, it is possible to suppress an increase in the melting temperature during the production of glass, and therefore, it is also possible to reduce the production cost of glass. In addition, it is possible to suppress a decrease in the visible light transmittance of the glass due to the Nb ₂ O ₅ component. Therefore, the upper limit of the content of the Nb ₂ O ₅ component is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.

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

The total amount of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) in the optical glass of the present invention is preferably 10.0% or more and 40.0% or more. the following.

In particular, by setting the total amount to 10.0% or more, the Abbe number of glass can be increased. Therefore, the lower limit of the total amount (mass sum) of the Ln ₂ O ₃ component is preferably 10.0%, more preferably 20.0%, and still more preferably 25.0%.

On the other hand, by reducing the total amount to 40.0% or less, the devitrification of glass can be reduced, and the use of expensive rare earths can be reduced, so the material cost of glass can be reduced. Therefore, the upper limit of the mass sum of the Ln ₂ O ₃ components is preferably 40.0%, more preferably 38.0%, and still more preferably 35.0%.

In the optical glass of the present invention, the ratio of the content of the ZnO component to the total amount of the Ln ₂ O ₃ component, the Ta ₂ O ₅ component, and the Nb ₂ O ₅ component is preferably 0.31 or more. As a result, the material cost is low, and the content of the ZnO component, which is a component that hardly affects the refractive index or Abbe number, is increased, thereby reducing the material cost of glass having a desired refractive index and Abbe number. Therefore, the lower limit of the mass ratio ZnO / (Ln ₂ O ₃ + Ta ₂ O ₅ + Nb ₂ O ₅ ) of the oxide conversion composition is preferably 0.31, more preferably 0.35, and even more preferably 0.38.

The upper limit of the mass ratio is not particularly limited, and may be preferably 2.00, more preferably 1.50, and even more preferably 1.00.

When the TiO ₂ component contains more than 0%, the refractive index of the glass can be increased, and the Abbe number can be adjusted to a lower arbitrary component. Therefore, the content of the TiO ₂ component may preferably be set to exceed 0%, more preferably set to exceed 0.5%, and even more preferably set to exceed 1.0%.

On the other hand, by making the content of the TiO ₂ component to be 20.0% or less, it is possible to suppress devitrification of the glass caused by the TiO ₂ component becoming a crystal nucleus, suppress a decrease in the Abbe number beyond the need, and reduce the TiO ₂ component. It contains visible glass transmittance due to the coloration of the glass. Therefore, the upper limit of the content of the TiO ₂ component is preferably 20.0%, more preferably 10.0%, still more preferably 6.0%, still more preferably 5.0%, still more preferably 4.2%, and even more preferably less than 3.94%.

The TiO ₂ component can be contained in glass using TiO ₂ or the like as a raw material.

When the content of WO ₃ is more than 0%, it can reduce the coloration of glass caused by other high refractive index components, and increase the refractive index, adjust the Abbe number to a lower level, and reduce the devitrification of glass. . Therefore, the content of the WO ₃ component may preferably be set to exceed 0%, more preferably set to exceed 1.0%, and even more preferably set to exceed 2.0%.

On the other hand, by setting the content of the WO ₃ component to 25.0% or less, it is possible to reduce the coloration of the glass due to the WO ₃ component and improve the visible light transmittance. Therefore, the upper limit of the content of the WO ₃ component is preferably 25.0%, more preferably 20.0%, still more preferably 13.0%, still more preferably less than 10.65%, and still more preferably less than 9.0%.

The WO ₃ component can be contained in glass using WO ₃ or the like as a raw material.

The total amount of the TiO ₂ component, the WO ₃ component, and the Nb ₂ O ₅ component in the optical glass of the present invention is preferably 20.0% or less. This makes it possible to suppress a decrease in the visible light transmittance or devitrification of the glass caused by excessively containing these components. Therefore, the upper limit of the mass and (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 20.0%, more preferably 17.5%, and even more preferably 16.0%.

Moreover, the lower limit of the mass and (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) may be 0%, but it is preferably more than 0%. By containing more than 0% by mass and (TiO ₂ + Nb ₂ O ₅ + WO ₃ ), even if the content of Ta ₂ O ₅ component or rare earth is reduced in order to reduce the material cost of glass, the refractive index and Dispersion makes it easy to secure an Abbe number of 40 or less. In addition, this can reduce devitrification of the glass. Therefore, the mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably more than 0%, more preferably more than 5.0%, and even more preferably more than 10.0%.

The ratio of the content of the TiO ₂ component in the optical glass of the present invention to the total amount of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component is preferably 0.50 or less. Thereby, even if a TiO ₂ component that deteriorates the transmittance is contained, the coloring can be reduced and the visible light transmittance can be improved. Therefore, the upper limit of the mass ratio of the oxide conversion composition TiO ₂ / (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 0.50, more preferably 0.48, and even more preferably 0.45.

The ratio of the total amount of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component to the content of the Ln ₂ O ₃ component in the optical glass of the present invention is preferably 0.16 or more. Thereby, among the components that increase the refractive index, the ratio of the TiO ₂ component, the Nb ₂ O ₅ component, and the WO ₃ component that reduces the Abbe number increases, so that the refractive index of the glass can be increased and the Abbe number can be reduced. Therefore, the lower limit of the mass ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ of the oxide conversion composition is preferably 0.16, more preferably 0.20, and even more preferably 0.25. The upper limit of the mass ratio is not particularly limited, but may be preferably 2.00, more preferably 1.50, and even more preferably 1.00.

When the content of SiO ₂ is more than 0%, it can increase the viscosity of the molten glass and reduce the devitrification of the glass. Therefore, the content of the SiO ₂ component may preferably be set to exceed 1.0%, more preferably to exceed 2.0%, and even more preferably to exceed 4.0%. In particular, by containing the SiO ₂ component and reducing the content of the Li ₂ O component, the devitrification resistance of the glass can be improved.

On the other hand, when the content of the SiO ₂ component is 15.0% or less, it is possible to suppress an increase in the glass transition point and suppress a decrease in the refractive index. Therefore, the upper limit of the content of the SiO ₂ component is preferably 15.0%, more preferably 10.0%, and still more preferably 8.0%.

The SiO ₂ component can be contained in glass using SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF _6, or the like as a raw material.

The ratio of the content of the SiO ₂ component to the content of the B ₂ O ₃ component in the optical glass of the present invention is preferably less than 1.00. This can reduce the devitrification of the glass caused by excessively containing the SiO ₂ component. Therefore, the mass ratio SiO ₂ / B ₂ O _{3 of the} oxide conversion composition is preferably less than 1.00, more preferably less than 0.90, and even more preferably less than 0.80. Furthermore, from the viewpoint of reducing the devitrification of the glass by containing the SiO ₂ component, the lower limit of the mass ratio SiO ₂ / B ₂ O ₃ may be preferably 0.05, more preferably 0.10, and even more preferably 0.20.

The Li ₂ O component is an arbitrary component that can improve the melting property of the glass and reduce devitrification when the glass is reheated when it contains more than 0%.

On the other hand, when the content of the Li ₂ O component is 5.0% or less, it is difficult to reduce the refractive index of the glass and reduce the devitrification of the glass caused by excessively containing the Li ₂ O component. In particular, the glass containing a Li ₂ O component tends to have a low refractive index and an Abbe number easily to become high. Therefore, in the glass containing the Li ₂ O component, in order to increase the refractive index and reduce the Abbe number, a large amount of the Nb ₂ O ₅ component is used as a component having a property of improving the glass transition point and a high material cost. High-refractive-index components (components that increase the refractive index). In the optical glass of the present invention, in order to reduce the content of the above-mentioned high refractive index component, a glass having a glass transition point capable of resisting pressure forming and having a desired refractive index and Abbe number is preferable to reduce Li ₂ O Content of ingredients. Therefore, the upper limit of the content of the Li ₂ O component is preferably 5.0%, more preferably 3.0%, still more preferably 1.0%, still more preferably less than 0.5%, still more preferably 0.35%, and It is preferably less than 0.3%.

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

When the MgO component, CaO component, SrO component, and BaO component are more than 0%, any component that can adjust the refractive index of the glass, improve the melting property of the glass, and reduce devitrification.

On the other hand, by setting the content of each of these components to be 10.0% or less, it is possible to suppress a reduction or devitrification of the refractive index of the glass beyond that required. Therefore, the upper limit of the content of each of the MgO component, the CaO component, the SrO component, and the BaO component is preferably 10.0%, more preferably 7.5% as the upper limit, further preferably less than 3.5%, and still more preferably 3.0. %.

MgO component, CaO component, SrO component and BaO component can use MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ , BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ etc. as raw materials .

In the optical glass of the present invention, the total amount of the RO component (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably less than 15.0%. This makes it possible to suppress a decrease in the refractive index of the glass or an increase in the liquidus temperature caused by excessively containing the RO component. Therefore, the total amount (sum of mass) of the RO component is preferably less than 15.0%, more preferably less than 10.0%, and even more preferably less than 7.0%.

The Na ₂ O component, the K ₂ O component, and the Cs ₂ O component are arbitrary components that can improve the meltability of the glass and reduce devitrification when the glass is reheated when the content exceeds 0%.

On the other hand, by reducing the content of each of these components to 5.0% or less, it is difficult to reduce the refractive index of the glass and reduce devitrification caused by excessively containing these components. Therefore, the upper limit of the content of each of the Na ₂ O component, the K ₂ O component, and the Cs ₂ O component is preferably 5.0%, more preferably 3.0%, and still more preferably 1.0%.

Na ₂ O, K ₂ O, and Cs ₂ O can be NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ , Cs ₂ CO ₃ , CsNO. ₃ etc. as raw materials.

In the optical glass of the present invention, the total amount of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, K, and Cs) is preferably 10.0% or less. This makes it difficult to reduce the refractive index of the glass and reduces devitrification caused by excessively containing the Rn ₂ O component. Therefore, the upper limit of the total amount (sum of mass) of the Rn ₂ O component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.

When the content of P ₂ O ₅ is more than 0%, it is an arbitrary component that can reduce the liquidus temperature of glass and reduce devitrification.

On the other hand, by reducing the content of the P ₂ O ₅ component to 10.0% or less, it is possible to suppress the decrease in the chemical durability, especially the water resistance, of the glass. Therefore, the upper limit of the content of the P ₂ O ₅ component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.

For 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%, it can increase the refractive index of glass and lower the liquidus temperature of glass.

On the other hand, by reducing the expensive GeO ₂ component, the effect of the present invention that can reduce the material cost of glass can be improved. Therefore, the upper limit of the content of the GeO ₂ component is preferably 10.0% or less, more preferably 5.0%, and even more preferably 1.0%.

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

When the content of Bi ₂ O ₃ is more than 0%, it is an arbitrary component that increases the refractive index and lowers the glass transition point.

On the other hand, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, the visible light transmittance of the glass can be improved by reducing the devitrification of the glass and reducing the coloration of the glass. Therefore, the upper limit of the content of the Bi ₂ O ₃ component is preferably 10.0%, more preferably 5.0%, and even more preferably 3.0%.

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

The ZrO ₂ component is an arbitrary component that contributes to high refractive index and low dispersion of the glass when it contains more than 0%, and can reduce devitrification of the glass. Therefore, the upper limit of the content of the ZrO ₂ component is preferably more than 0%, more preferably 0.1%, still more preferably 0.5%, and still more preferably 1.0%.

On the other hand, by setting the content of the ZrO ₂ component to be 15.0% or less, it is possible to suppress an increase in the manufacturing cost of glass by suppressing an increase in the melting temperature during glass production. Therefore, the upper limit of the content of the ZrO ₂ component is preferably 15.0%, more preferably 10.0%, and even more preferably 5.0%.

For the ZrO ₂ component, ZrO ₂ , ZrF _4, 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 at more than 0%, they can improve the chemical durability of the glass and reduce any devitrification when the glass is melted.

On the other hand, by making the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to be 5.0% or less, devitrification of glass caused by excessively containing these components can be reduced. In addition, by reducing expensive Ga ₂ O ₃ components, the material cost of glass can be reduced. Therefore, the upper limit of the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 5.0%, more preferably 3.0% or less, and still more preferably 1.0%.

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 and the like can be used as raw materials.

When the content of TeO ₂ is more than 0%, it is possible to increase the refractive index of the glass and lower the glass transition point.

On the other hand, by reducing the content of the TeO ₂ component to 15.0% or less, alloying of the TeO ₂ component with the melting equipment (especially noble metals such as Pt) can be reduced, so that the life of the melting equipment can be extended. In addition, by reducing expensive TeO ₂ components, the material cost of glass can be reduced. Therefore, the upper limit of the content of the TeO ₂ component is preferably 15.0%, more preferably 11.9% or less, and still more preferably 7.0% or less.

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

When the content of SnO ₂ is more than 0%, it is an arbitrary component that can clarify molten glass and improve the visible light transmittance of glass.

On the other hand, by setting the content of the SnO ₂ component to 1.0% or less, it is possible to make it difficult for the color of the glass or the devitrification of the glass to occur due to the reduction of the molten glass. In addition, since the alloying of the SnO ₂ component and the melting equipment (especially noble metals such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the upper limit of the content of the SnO ₂ component is preferably 1.0%, more preferably 0.5%, and even more preferably 0.3%.

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

The CeO ₂ component is an arbitrary component that can clarify the molten glass when the content of the CeO ₂ component exceeds 0%.

On the other hand, when the content of the CeO ₂ component is 1.0% or less, a decrease in visible light transmittance due to coloration can be suppressed. Therefore, the upper limit of the content rate of the CeO ₂ component is preferably 1.0%, more preferably 0.5%, and even more preferably 0.3%.

As the CeO ₂ component, CeO ₂ , Ce (OH) _3, or the like can be used as a raw material.

The Sb ₂ O ₃ component is an arbitrary component that increases the visible light transmittance of the glass when it contains more than 0%, and can defoam when the glass is melted.

On the other hand, when the content of the Sb ₂ O ₃ component is 1.0% or less, excessive foaming when the glass is melted can be suppressed. In addition, since the Sb ₂ O ₃ component is difficult to alloy with a melting device (especially a noble metal such as Pt), a long life of the melting device can be achieved. When the content of the Sb ₂ O ₃ component is too large, the visible light transmittance of the glass is reduced. Therefore, the upper limit of the content of the Sb ₂ O ₃ component is preferably 1.0%, more preferably 0.5%, and even more preferably less than 0.1%.

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

In addition, the component which clarifies glass and performs defoaming is not limited to the above-mentioned Sb ₂ O ₃ component, and a known clarifying agent, defoaming agent, or a combination thereof may be used in the field of glass manufacturing.

<About ingredients that should not be contained>

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

As long as the characteristics of the glass of the present invention are not impaired, other components may be added as necessary. Among them, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, Lu, each of the transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo is separate or When the compound is contained in a small amount, the glass is also colored and has a property of absorbing specific wavelengths in the visible light region. Therefore, it is particularly preferable that the glass is substantially not contained in the optical glass using the wavelength in the visible light region.

Furthermore, lead compounds such as PbO and the components of Th, Cd, Tl, Os, Be, and Se have tended to be controlled and used as harmful chemical substances in recent years. Not only the glass manufacturing steps, but also the processing steps, and after productization All measures must be taken to deal with environmental problems. Therefore, when attention is paid to environmental impacts, it is preferable not to include them substantially except for inevitable mixing. As a result, the environment glass is not substantially contained in the optical glass. Therefore, the optical glass can be manufactured, processed, and discarded without taking special environmental measures.

Since the range of the content of each component in the present invention is expressed in terms of mass% relative to the total mass of glass in terms of oxide conversion, it is not directly expressed as mole%. In the present invention, the existence of The composition represented by the mole% of each component in the glass composition of various characteristics is roughly set to the following values in terms of oxide conversion composition: B ₂ O ₃ component 5.0 to 70.0 mole%, La ₂ O ₃ component 3.0 ~ 20.0 mole%, and ZnO component 15.0 ~ 60.0 mole%, and Gd ₂ O ₃ component 0 ~ 3.0 mole%, Y ₂ O ₃ component 0 ~ 5.0 mole%, Yb ₂ O ₃ component 0 ~ 3.0 mole Ear%, Lu ₂ O ₃ composition 0 to 3.0 mole%, Ta ₂ O ₅ composition 0 to 7.0 mole%, Nb ₂ O ₅ composition 0 to 20.0 mole%, TiO ₂ composition 0 to 40.0 mole%, WO ₃ components 0 to 25.0 mole%, SiO ₂ component 0 to 30.0 mole%, Li ₂ O component 0 to 30.0 mole%, MgO component 0 to 50.0 mole%, CaO component 0 to 40.0 mole%, SrO component 0 ~ 30.0 mole%, BaO component 0 ~ 35.0 mole%, Na ₂ O component 0 ~ 25.0 mole%, K ₂ O component 0 ~ 20.0 mole%, Cs ₂ O component 0 ~ 10.0 mole%, P component ₂ O ₅ 0 to 15.0 mole%, GeO ₂ 0 to 10.0 mole ingredients%, Bi ₂ O ₃ content of 0 to 5.0 mole%, ZrO ₂ into 0 to 18.0 mole%, Al ₂ O ₃ component 0 to 15.0 mole%, Ga ₂ O ₃ component to 5.0 mole 0%, TeO ₂ 0 to 25.0 mole ingredients%, SnO ₂ 0 to 0.3 mole% component Or Sb ₂ O ₃ component 0 ~ 1.0 mole%.

[Production method]

The optical glass of the present invention is produced, for example, as follows. That is, it is prepared as follows: the above raw materials are uniformly mixed so that each component reaches a specific content range, the prepared mixture is put into a platinum crucible, and an electric furnace is used at 1200 to 1400 ° C according to the ease of melting of the glass composition. It is melted in the temperature range for 3 to 4 hours. After being stirred and homogenized, it is reduced to an appropriate temperature, and then cast into a mold and slowly cooled.

[Physical properties]

The optical glass of the present invention preferably has a high refractive index and a high Abbe number (low dispersion). In particular, the lower limit of the refractive index (n _d ) of the optical glass of the present invention is preferably 1.75, more preferably 1.78, and even more preferably 1.80. The upper limit of the refractive index may also be preferably 2.20, more preferably 2.10, and even more preferably 2.00. The lower limit of the Abbe number (ν _d ) of the optical glass of the present invention is preferably 30, more preferably 32, and even more preferably 35, and the upper limit is preferably 40, and more preferably It is 39.8, More preferably, it is 39.5.

By having the above-mentioned high refractive index, even if the optical element is reduced in thickness, a large amount of light refraction can be obtained. Moreover, by having the above-mentioned low dispersion, even if it is a single lens, the focus shift (chromatic aberration) due to the wavelength of light is reduced. Further, by having the above-mentioned low dispersion, for example, when it is combined with an optical element having a high dispersion (low Abbe number), high imaging characteristics can be achieved.

Therefore, the optical glass of the present invention is more useful in optical design, in particular, it can achieve high imaging characteristics, etc., and realize the compactness of the optical system To expand the freedom of optical design.

The optical glass of the present invention preferably has a high transmittance of visible light, in particular, the transmittance of light on the short-wavelength side of visible light is high, thereby reducing coloration. In particular, in the sample of the optical glass of the present invention having a thickness of 10 mm, the upper limit of the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% may be preferably set to 400 nm, and more preferably set to 380. nm, and more preferably 360 nm. In addition, in the sample of the optical glass having a thickness of 10 mm, the upper limit of the shortest wavelength (λ ₈₀ ) showing a spectral transmittance of 80% may be preferably set to 500 nm, more preferably 490 nm. Furthermore, it is more preferably 480 nm. As a result, the absorption end of the glass is shifted from the visible light region, which can improve the transparency of the glass with respect to the light of a wider wavelength in the visible light region. Therefore, the optical glass can be preferably used for an optical element such as a lens that transmits visible light .

[Preforms and Optical Elements]

A glass molded body can be produced from the manufactured optical glass by a method such as reheat press molding or precision press molding. That is, a glass molded body can be produced by grinding and grinding a blank or a glass block formed of optical glass to obtain the shape of an optical element, and reheating a blank or a glass block formed of optical glass. The method of forming (reheating and pressing) and grinding and grinding the obtained glass formed body, and a pre-formed body material obtained by cutting and grinding a blank or a glass block using an ultra-precision processing mold, or A known method for obtaining a shape of an optical element by forming a preformed body (precision press forming) formed by suspension forming or the like. In addition, the method of manufacturing a glass forming body is not limited to these methods.

The glass molded body produced in the above manner is useful in various optical elements and optical designs. In particular, it is preferred that the optical glass of the present invention is used to produce a lens, an optical element, or a lens using a method such as precision press molding. Accordingly, when used in an optical device such as a camera or a projector that transmits visible light through an optical element, high-definition and high-precision imaging characteristics can be realized, and the optical system of these optical devices can be miniaturized.

[Example]

The composition of the examples (No. 1 to No. 72) and comparative examples (No. A) of the present invention, and the refractive index (n _d ), Abbe number (ν _d ), and spectral transmittance of the glasses The wavelengths (λ ₅ and λ ₈₀ ) shown as 5% and 80% are shown in Tables 1 to 10. In addition, the following embodiments are for illustration purposes only and are not limited to these embodiments.

The glasses of these examples and comparative examples are selected as high-purity raw materials used for ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc. The raw materials of each component were weighed and uniformly mixed so as to have the composition ratios of each of the examples and comparative examples shown in Tables 1 to 10, and then put into a platinum crucible. After melting in a temperature range of 1100 to 1500 ° C for 2 to 5 hours, it is homogenized with stirring to defoam, etc., and then cast into a mold and slowly cooled to produce glass.

Here, the refractive index and Abbe number of the glass in the examples and comparative examples were measured according to the Japanese Optical Glass Industrial Standard (JOGIS) 01-2003. In addition, as the glass used in this measurement, a slow cooling lowering rate set as an annealing condition was used. Glass at -25 ° C / hr and treated in a slow cooling furnace.

In addition, the visible light transmittance of the glasses of the examples and comparative examples was measured according to the standard of the Japan Optical Glass Industry Association JOGIS02. Furthermore, in the present invention, by measuring the transmittance of the glass, it is possible to determine the presence and extent of the coloration of the glass. Specifically, in accordance with JIS (Japanese Industrial Standard) Z8722, a parallel polished product having a thickness of 10 ± 0.1 mm was measured at a spectral transmittance of 200 to 800 nm to obtain λ ₅ (transmittance of 5%). Wavelength) and λ ₈₀ (wavelength at 80% transmittance).

The optical glass systems λ ₈₀ (wavelength at 80% transmittance) of the examples of the present invention are all 500 nm or less, and more specifically 450 nm or less. In addition, the optical glass systems λ ₅ (wavelengths at a transmittance of 5%) of the examples of the present invention are all 400 nm or less, and more specifically 350 nm or less. Therefore, it can be seen that the optical glass of the embodiment of the present invention has less coloration and higher visible light transmittance.

The refractive index (n _d ) of the optical glass system according to the embodiment of the present invention is all 1.75 or more, and more specifically 1.80 or more, which is within a desired range.

In addition, the optical glass-based Abbe numbers (ν _d ) of the examples of the present invention are all 30 or more, more specifically 35 or more, and the Abbe numbers (ν _d ) are 40 or less, and more specifically 39. In the following, it is within a desired range.

In addition, compared with the glass of Comparative Example (No. A), the optical glass of the example of the present invention has a smaller content of the Ta ₂ O ₅ component and a larger content of the ZnO component, so the material cost is reduced.

Therefore, it can be seen that the refractive index (n _d ) and Abbe number (ν _d ) of the optical glass system in the examples of the present invention are within a desired range, can be produced at low cost, have less coloration, and have high visible light transmittance. Therefore, it is speculated that the optical glass of the embodiment of the present invention can be preferably used for the purpose of transmitting visible light.

Furthermore, the optical glass according to the embodiment of the present invention is used for grinding and grinding after reheating and pressure forming, and is processed into the shape of a lens and a cymbal. In addition, the optical glass according to the embodiment of the present invention is used to form a preform for precision press molding, and the preform for precision press molding is precision press processed into the shape of a lens and a cymbal. In either case, there will be no problems with fusion with the shaped block, or problems such as milk whitening and devitrification in the glass after heating and softening, and it can be processed into various lens and grate shapes in a stable manner.

In the above, the present invention has been described in detail for the purpose of illustration. However, it should be understood that this embodiment is only for the purpose of illustration, and the industry can make many changes without departing from the idea and scope of the present invention.

Claims (15)

An optical glass containing 5.0 to 40.0% of a B ₂ O ₃ component, 10.0 to 40.0% of a La ₂ O ₃ component, and 10.0 to 40.0% of a ZnO component relative to the total mass of the glass in terms of oxide conversion composition. The content of TiO ₂ component exceeding 1.0% and less than 20.0%, the content of Li ₂ O component is less than 0.5%, the content of Ta ₂ O ₅ component is 15.0% or less, the content of Nb ₂ O ₅ component is 15.0% or less, WO ₃ The content of the component is 13.0% or less, and the mass of the Ln ₂ O ₃ component (where Ln is one or more selected from the group consisting of La, Gd, Y, Yb, and Lu) is 10.0% or more and 40.0% or less The mass sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is more than 5.0% and less than 20.0%. The mass ratio of the oxide conversion composition of SiO ₂ / B ₂ O ₃ is 0.272 or more and less than 1.00, which is 1.75 or more. The refractive index (n _d ) has an Abbe number (ν _d ) of 30 or more and 40 or less. For example, the optical glass according to claim 1, which contains the Gd ₂ O ₃ component 0-5.0% Y ₂ O ₃ component 0-5.0% Yb ₂ O ₃ component with respect to the total mass of the oxide-converted glass in mass%. 0 ~ 5.0% Lu ₂ O ₃ composition 0 ~ 5.0%. For example, the optical glass of claim 2, wherein the total mass of (Gd ₂ O ₃ + Y ₂ O ₃ + Yb ₂ O ₃ + Lu ₂ O ₃ + Ta ₂ O ₅ ) with respect to the oxide-converted composition is 15.0% the following. For example, the optical glass of claim 3, wherein the mass ratio ZnO / (Ln ₂ O ₃ + Ta ₂ O ₅ + Nb ₂ O ₅ ) of the oxide conversion composition is 0.31 or more. For example, the optical glass of claim 2, wherein the mass ratio of the oxide conversion composition TiO ₂ / (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is 0.50 or less. For example, the optical glass of claim 2, wherein the mass ratio (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / Ln ₂ O ₃ of the oxide conversion composition is 0.16 or more. For example, the optical glass according to claim 1, which contains more than 2.0% to 15.0% of the SiO ₂ component in terms of mass% relative to the total mass of the glass in terms of the oxide conversion composition. For example, the optical glass of claim 1, which contains the MgO component 0 to 10.0% CaO component 0 to 10.0% SrO component 0 to 10.0% BaO component 0 to 10.0 with respect to the total mass of the glass in terms of oxide conversion composition. %. For example, the optical glass of claim 8, wherein the mass of the RO component (where R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) and the total mass of the glass relative to the oxide conversion composition Up to 15.0%. For example, the optical glass according to claim 1, which is relative to the total mass of the glass in terms of oxide conversion, and further contains: Na ₂ O component 0 to 5.0% K ₂ O component 0 to 5.0% Cs ₂ O component 0 to 5.0 %, And the total mass of the Rn ₂ O component (where Rn is one or more selected from the group consisting of Li, Na, K, and Cs) relative to the total mass of the glass in terms of oxide conversion is 10.0% or less . For example, the optical glass of claim 1, which contains the P ₂ O ₅ component 0 to 10.0% GeO ₂ component 0 to 10.0% Bi ₂ O ₃ component 0 to relative to the total mass of the glass in terms of oxide conversion composition. 10.0% ZrO ₂ component 0 to 15.0% Al ₂ O ₃ component 0 to 5.0% Ga ₂ O ₃ component 0 to 5.0% TeO ₂ component 0 to 15.0% SnO ₂ component 0 to 1.0% Sb ₂ O ₃ component 0 to 1.0% . An optical element comprising the optical glass according to any one of claims 1 to 11. A preform for precision press forming, comprising the optical glass according to any one of claims 1 to 11. An optical element obtained by precision press-molding a preform for precision press-molding as in claim 13. The manufacturing method of a glass forming body which softens the optical glass as described in any one of Claims 1-11 and press-molds in a mold.