CN106167354B

CN106167354B - Optical glass and optical element

Info

Publication number: CN106167354B
Application number: CN201610317889.5A
Authority: CN
Inventors: 小栗史裕
Original assignee: Ohara Inc
Current assignee: Ohara Inc
Priority date: 2015-05-18
Filing date: 2016-05-12
Publication date: 2021-05-07
Anticipated expiration: 2036-05-12
Also published as: JP2016216282A; JP6664826B2; CN106167354A

Abstract

The purpose of the present invention is to provide an optical glass that has a refractive index and an Abbe number both within a desired range and that contributes to weight reduction and stability of an optical instrument at a lower cost. The optical glass contains B in mass percent₂O₃5.0 to 30.0% of La₂O₃30.0 to 60.0%, the sum of the mass of the oxides (ZrO) based₂+Nb₂O₅+Ta₂O₅+WO₃) Below 20.0%. The optical glass has a refractive index nd of 1.85 or more, an Abbe number vd of 30 or more, and a specific gravity of 5.00 or less.

Description

Optical glass and optical element

Technical Field

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

Background

In recent years, the digitalization and high definition of devices using optical systems have been rapidly advancing, and in the field of various optical devices such as photographic equipment such as digital cameras and video cameras, and video playback (projection) devices such as projectors and projection televisions, there has been an increasing demand for reducing the number of optical elements such as lenses and prisms used in optical systems, and for reducing the weight and size of the entire optical system.

Among optical glasses used for manufacturing optical elements, in particular, there is a very high demand for high-refractive-index, low-dispersion glasses that can achieve weight reduction and size reduction of an entire optical system and have a refractive index (nd) of 1.75 or more and 2.00 or less and an abbe number (ν d) of 23 or more and 45 or less. As such a glass having a high refractive index and low dispersion, glass components described in patent documents 1 and 2 are widely known.

[ patent document 1 ] Japanese patent document laid-open No. 2006-016293

[ patent document 2 ] Japanese patent document laid-open No. 2011-

Technical problem to be solved by the invention

As a method for manufacturing an optical element from an optical glass, the following methods are known: for example, a method of grinding and polishing a gob or a glass gob made of optical glass to obtain the shape of an optical element; a method of obtaining a glass molded body by reheat molding (reheat press molding) of a gob or a glass gob made of optical glass, and grinding and polishing the glass molded body; and a method of obtaining the shape of an optical element by molding (precision press molding) a preform obtained from a gob or a glass gob in an ultraprecision-machined mold. In any of the above methods, it is required to obtain stable glass when forming gobs or glass gobs from molten glass raw materials. Here, when the stability against devitrification (resistance to devitrification) of the glass constituting the obtained gob or glass gob is lowered and crystals are formed inside the glass, a glass suitable as an optical element cannot be obtained.

In order to reduce the material cost of the optical glass, it is required that the raw material cost of each component constituting the optical glass is as low as possible. However, it is difficult for the glasses described in patent documents 1 and 2 to sufficiently satisfy such a requirement.

Further, the glasses described in patent documents 1 and 2 have a problem that the glass has a high specific gravity and the optical element has a high mass. That is, when these glasses are used in optical instruments such as cameras and projectors, the quality of the entire optical instrument tends to be large.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a glass having a refractive index and an abbe number both within a desired range at a lower cost and contributing to weight reduction and stability of an optical instrument.

Disclosure of Invention

The present inventors have made extensive experiments and studies to solve the above problems, and as a result, they have found that B is contained as an essential component₂O₃Component (A) and La₂O₃In the glass of component (B), by making it contain ZrO in a desired amount₂Component (B) and Nb₂O₅Component (A) Ta₂O₅Component (A) and WO₃The present invention has been completed in view of the above finding that a stable glass having a desired high refractive index and a desired high abbe number can be obtained, the material cost of the glass can be reduced, and the specific gravity of the glass can be reduced. Specifically, the present invention provides the following optical glasses.

(1) An optical glass comprising B in an amount of mass% calculated on the basis of the oxide of the composition₂O₃5.0 to 30.0% of La₂O₃30.0 to 60.0%, the sum of the mass of the oxides (ZrO) based₂+Nb₂O₅+Ta₂O₅+WO₃) 20.0% or less, a refractive index nd of 1.85 or more, an Abbe's number vd of 30 or more, and a specific gravity of 5.00 or less.

(2) The optical glass according to the above (1), wherein the glass composition is characterized in that, as calculated by mass% of the composition in terms of oxides,

Y₂O₃the component(s) is (are) 0 to 20.0%,

Gd₂O₃the component(s) is (are) 0 to 10.0%,

Yb₂O₃the component is 0-15.0%.

(3) The optical glass according to the above (1) or (2), wherein the glass composition is calculated as mass% in terms of oxide,

SiO₂the component is 0-15.0%,

TiO₂the component is 0-30.0%,

ZrO₂the component is 0-15.0%,

WO₃the component(s) is (are) 0 to 10.0%,

0 to 20.0 percent of ZnO,

MgO component of 0 to 10.0%,

CaO component is 0-15.0%,

0 to 15.0% of SrO,

BaO content is 0-15.0%,

Li₂0 to 10.0% of an O component,

Na₂0 to 10.0% of an O component,

K₂0 to 10.0% of an O component,

Ta₂O₅the component(s) is (are) 0 to 10.0%,

Nb₂O₅the component(s) is (are) 0 to 10.0%,

ZrO₂the component is 0-15.0%,

P₂O₅the component(s) is (are) 0 to 10.0%,

GeO₂the component(s) is (are) 0 to 10.0%,

Al₂O₃the component(s) is (are) 0 to 10.0%,

Ga₂O₃the component(s) is (are) 0 to 10.0%,

Bi₂O₃the component(s) is (are) 0 to 10.0%,

TeO₂0 to 5.0% of a component, and

SnO₂the component(s) is (are) 0 to 1.0%,

relative to removing Sb₂O₃Components other than the component (B), calculated as mass%, Sb₂O₃The component is 0-1.0%.

(4) The optical glass according to any one of the above (1) to (3), wherein the glass is characterized in that, as calculated by mass% based on an oxide,

Ln₂O₃the sum of the mass of the components is 45.0-70.0%, wherein Ln is more than 1 selected from the group consisting of La, Gd, Y and Yb; rn₂The sum of the mass of O components is0 to 15.0%, wherein Rn is more than 1 selected from the group consisting of Li, Na and K; the sum of the RO components is0 to 25.0% by mass, wherein R is at least 1 selected from the group consisting of Mg, Ca, Sr and Ba.

(5) The optical glass according to any one of the above (1) to (4), wherein the wavelength λ representing a spectral transmittance of 70%₇₀Below 480 nm.

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

(7) A preform which is composed of the optical glass described in any one of the above (1) to (5) and which is used for polishing and/or precision press molding.

(8) An optical element, characterized in that the preform of (7) above is subjected to precision press working. Effects of the invention

According to the present invention, an optical glass having a refractive index and an abbe number both within a desired range and contributing to weight reduction and stability of an optical instrument can be obtained at a lower cost.

Detailed Description

The optical glass of the present invention is prepared byB is contained in the glass in an amount of mass% based on the total mass of the glass in terms of oxide₂O₃5.0-30.0% of La₂O₃The component (C) is 30.0 to 60.0%, and the sum of the oxide-based masses (ZrO) is calculated₂+Nb₂O₅+Ta₂O₅+WO₃) Below 20.0%, thereby reducing Gd in particular₂O₃And Yb₂O₃And a plurality of rare earth elements which are expensive and increase the specific gravity of the glass, and can obtain a high refractive index and abbe number and suppress an increase in the liquidus temperature. Therefore, an optical glass having a high devitrification resistance and contributing to weight reduction of an optical device having a refractive index of 1.85 or more and an abbe number of 30 or more and 50 or less and having a specific gravity of 5.00 or less can be obtained at a lower cost.

The optical glass of the present invention is obtained by the following steps, which are not intended to limit the scope of the present invention. Note that, although the description of the parts to be described repeatedly may be appropriately omitted, the gist of the invention is not limited thereto.

[ glass composition ]

The composition ranges of the respective components constituting the optical glass of the present invention are as follows. In the present specification, unless otherwise specified, the contents of each component are expressed in mass% with respect to the total mass of the glass in terms of oxides. Here, the "composition in terms of oxides" means that, assuming that all of the oxides, complex salts, metal fluorides, and the like used as the raw materials of the glass composition components of the present invention are decomposed and converted into oxides during melting, the total mass of the generated oxides is defined as 100 mass%, and the composition of each component contained in the glass is expressed.

< essential Components, optional Components >

B₂O₃The component (b) is an essential component which is indispensable for forming an oxide as a glass.

In particular, by containing 5.0% or more of B₂O₃The component (B) can improve the devitrification resistance of the glass and reduce the dispersion of the glass. Thus, B₂O₃The content of the component (B) is preferably 5.0% or less, more preferably 5.0% or less, still more preferably 8.5% or less, and still more preferably 10.5% or less.

On the other hand, by making B₂O₃When the content of the component is 30.0% or less, a larger refractive index can be obtained easily, and a decrease in chemical durability can be suppressed. Thus, B₂O₃The content of the component (B) is preferably up to 30.0%, more preferably up to 25.0%, still more preferably up to 20.0%.

B₂O₃Component (C) as a raw material, H can be used₃BO₃、Na₂B₄O₇、Na₂B₄O₇·10H₂O、BPO₄And the like.

La₂O₃The component (b) is a component capable of increasing the refractive index of the glass and reducing the dispersion (increasing the abbe number). In particular, by containing 30.0% or more of La₂O₃The composition can obtain a desired high refractive index. Thus, La₂O₃The content of the component (B) is preferably 30.0% or less, more preferably 35.0% or less, still more preferably 37.0% or less, and still more preferably 40.0% or less.

On the other hand, by making La₂O₃When the content of the component (B) is 60.0% or less, devitrification resistance of the glass can be improved. Thus, La₂O₃The upper limit of the content of the component (B) is preferably 60.0%, more preferably 55.0%, still more preferably 50.0%.

La₂O₃Component (A) La can be used as a raw material₂O₃、La(NO₃)₃·XH₂O (X is an arbitrary integer), and the like.

In the optical glass of the present invention, ZrO₂Component (B) and Nb₂O₅Component (A) Ta₂O₅Component (A) and WO₃The sum of the contents (sum of mass) of the components is preferably 20.0% or less. Accordingly, the specific gravity can be reduced while maintaining a high refractive index and a high abbe number, and the visible light transmittance can be suppressed. Therefore, sum of mass (ZrO)₂+Nb₂O₅+Ta₂O₅+WO₃) The upper limit is preferably 20.0%, more preferably 10.0%, and still more preferably 7.0%.

Y₂O₃The component (b) is an arbitrary component which can reduce the specific gravity while keeping a high refractive index and a high abbe number when the content exceeds 0%, and the material cost of the glass can be suppressed. The Y is₂O₃The component (A) is a useful component for the optical glass of the present invention because the material cost is low in rare earth elements and the specific gravity is easily reduced compared with other rare earth elements. Thus, Y₂O₃The content of the component (B) is preferably more than 0%, more preferably more than 1.0%, still more preferably more than 3.0%, and further preferably more than 5.0%.

On the other hand, by making Y₂O₃When the content of the component (C) is 20.0% or less, the decrease in refractive index of the glass can be suppressed, and the devitrification resistance of the glass can be improved. Thus, Y₂O₃The content of the component (B) is preferably 20.0% or more, more preferably 15.0% or more, still more preferably 13.0% or more, and still more preferably 10.0% or more.

Y₂O₃Component (B) as a raw material, Y can be used₂O₃、YF₃And the like.

Gd₂O₃The component (b) is an optional component which can increase the refractive index of the glass and can increase the Abbe number when the content exceeds 0%.

On the other hand, in rare earth elements, in particular, by using relatively expensive Gd₂O₃The content of the component is reduced to less than 10.0%, so that the material cost of the glass is reduced, and the glass can be manufacturedCheaper optical glass. In addition, an excessive increase in the abbe number of the glass can be suppressed. Thus, Gd₂O₃The upper limit of the content of the component (B) is preferably 10.0%, more preferably 9.0%, still more preferably 8.0%.

In particular, by using Gd₂O₃The content of the component (b) is 3.0% or less, which contributes to further reduction in cost and specific gravity. Therefore, Gd is added to the alloy to reduce the material cost₂O₃The upper limit of the content of the component (B) is preferably 3.0%, more preferably less than 1.0%.

Gd₂O₃Component (B) Gd may be used as a raw material₂O₃、GdF₃And the like.

Yb₂O₃The component is an arbitrary component which can increase the refractive index of the glass and reduce the dispersion when the content exceeds 0%.

On the other hand, by making Yb₂O₃When the content of the component (B) is 10.0% or less, devitrification resistance of the glass can be improved. Thus, Yb₂O₃The upper limit of the content of the component (B) is preferably 9.0%, more preferably 8.0%.

In particular, by making Yb₂O₃The content of the component (b) is 3.0% or less, which contributes to further reduction in cost and specific gravity. Therefore, Yb is required to further reduce the material cost₂O₃The upper limit of the content of the component (B) is preferably 3.0%, and more preferably less than 1.0%.

Yb₂O₃Component (B) Yb can be used as a raw material₂O₃And the like.

Ln₂O₃The sum of the contents (sum of mass) of the components is preferably 45.0% to 70.0%, where Ln is 1 or more selected from the group consisting of La, Gd, Y and Yb.

In particular, when the sum of the masses is 45.0% or more, the dispersion of the glass can be reduced. Thus, Ln₂O₃The sum of the components is preferably 45.0% or less, more preferably 48.0% or less, still more preferably 50.0% or less, and still more preferably 54.0% or less.

On the other hand, when the sum is 70.0% or less, the liquidus temperature of the glass can be lowered, and therefore resistance to devitrification can be improved. Thus, Ln₂O₃The sum of the components is preferably 70.0% by mass, more preferably 65.0% by mass, and still more preferably 60.0% by mass.

Ta₂O₅When the content of the component (b) exceeds 0%, the refractive index and devitrification resistance of the glass can be improved.

On the other hand, by using relatively expensive Ta₂O₅The content of the component is reduced to 10.0% or less, so that the material cost of the glass is reduced, and thus the optical glass can be manufactured at a lower cost. Further, since the melting temperature of the raw material is lowered, energy required for melting the raw material is reduced, and thus the production cost of the optical glass can be reduced. Thus, Ta₂O₅The upper limit of the content of the component (B) is preferably 10.0%, more preferably 9.0%, still more preferably 8.0%. In particular, Ta is one of the most important factors in producing optical glass having a lower specific gravity and being inexpensive₂O₅The content of the component (B) is preferably 5.0% or more, more preferably 4.0% or more, still more preferably less than 1.0%, and most preferably not contained.

Ta₂O₅Component (A) Ta can be used as a raw material₂O₅And the like.

WO₃When the content of the component (b) exceeds 0%, the dyeing of the glass due to other high refractive index components can be reduced, and the refractive index and the devitrification resistance of the glass can be improved. Thus, WO₃The content of the component (B) is preferably more than 0%, more preferably 0.1% or less, still more preferably 0.5% or less.

Another one isBy subjecting WO₃The content of the component (A) is 10.0% or less, which can contribute to reduction of WO₃The components cause staining of the glass and improve visible light transmittance, and reduce cost and specific gravity. Thus, WO₃The upper limit of the content of the component (B) is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%.

WO₃Component (A) WO may be used as a raw material₃And the like.

Nb₂O₅When the content of the component (b) exceeds 0%, the refractive index and devitrification resistance of the glass can be improved. Further, since the specific gravity is reduced and the material cost of the glass is reduced, the optical glass can be manufactured at a lower cost.

On the other hand, by using Nb₂O₅The content of the component (B) is 10.0% or less, and Nb is inhibited₂O₅When the content of the component is too high, the glass has a reduced devitrification resistance and a reduced visible light transmittance. Thus, Nb₂O₅The upper limit of the content of the component (B) is preferably 10.0%, more preferably 8.0%, still more preferably 5.0%.

Nb₂O₅Component (b) Nb is used as a raw material₂O₅And the like.

TiO₂When the content of the component (b) exceeds 0%, the refractive index of the glass can be increased, the Abbe number can be decreased, and the devitrification resistance can be improved. Thus, TiO₂The content of the component (B) is preferably more than 0%, more preferably 3.0% or less, and still more preferably 5.0% or less.

On the other hand, by making TiO₂The content of (b) is 30.0% or less, the coloring of the glass can be reduced and the visible light transmittance can be improved, and the excessive decrease of the abbe number of the glass can be suppressed. In addition, the formation of TiO can be suppressed₂Devitrification due to too high content of ingredients. Thus, TiO₂The upper limit of the content of the component (B) is preferably 30.0%, more preferablyThe upper limit is 20.0%, more preferably 15.0%, and still more preferably less than 13.0%.

TiO₂Component (C), TiO can be used as a raw material₂And the like.

SiO₂When the content of the component (b) exceeds 0%, the viscosity of molten glass can be increased, the staining of the glass can be reduced, and the devitrification resistance can be improved. Thus, SiO₂The content of the component (B) is preferably more than 0%, more preferably 3.0% or less, and still more preferably 5.0% or less.

On the other hand, by using SiO₂When the content of the component (B) is 15.0% or less, the increase in glass transition temperature and the decrease in refractive index can be suppressed. Thus, SiO₂The content of the component (B) is preferably 15.0% or more, more preferably 13.0% or more, still more preferably 10.0% or more, and still more preferably 8.0% or more.

SiO₂Component (C), SiO can be used as a raw material₂、K₂SiF₆、Na₂SiF₆And the like.

In addition, with respect to B₂O₃Component (B) SiO₂The ratio of the content (mass ratio) of the components is preferably 0.40 to 0.80.

In particular, by setting the ratio to 0.40 or more, the devitrification resistance of the glass can be improved. Therefore, mass ratio (SiO)₂)/(B₂O₃) The lower limit is preferably 0.40, more preferably 0.50, and still more preferably 0.55.

On the other hand, by setting the ratio to 0.80 or less, a higher refractive index can be easily obtained. Therefore, mass ratio (SiO)₂)/(B₂O₃) The upper limit is preferably 0.80, more preferably 0.75, and still more preferably 0.70.

In addition, with respect to La₂O₃Component (b) Gd₂O₃Component (A) and Y₂O₃The components of the components are mixed and stirred,Y₂O₃component (C), TiO₂The ratio (mass ratio) of the contents of the component (i) and the ZnO component (i) is preferably 0.40 to 1.00.

In particular, by setting the ratio to 0.40 or more, the specific gravity can be reduced. Thus, mass ratio (Y)₂O₃+TiO₂+ZnO)/(La₂O₃+Gd₂O₃+Y₂O₃) The lower limit is preferably 0.30, more preferably 0.35, and still more preferably 0.40.

On the other hand, when the ratio is 0.80 or less, the occurrence of dyeing, a decrease in viscosity, and streaks due to an excessively high content can be suppressed. Thus, mass ratio (Y)₂O₃+TiO₂+ZnO)/(La₂O₃+Gd₂O₃+Y₂O₃) The upper limit is preferably 0.80, more preferably 0.70, and still more preferably 0.60.

In addition, with respect to TiO₂Component (C) ZrO₂Component (B) and Nb₂O₅Component (A) Ta₂O₅Component (B) and WO₃Component (A) WO₃The ratio of the content (mass ratio) of the components is preferably 0.03 to 0.22.

In particular, when the ratio is 0.03 or more, devitrification resistance of the glass can be improved. Therefore, mass ratio (WO)₃)/(TiO₂+ZrO₂+Nb₂O₅+Ta₂O₅+WO₃) The lower limit is preferably 0.03, more preferably 0.035, and still more preferably 0.04.

On the other hand, when the ratio is 0.22 or less, the glass can be prevented from being dyed due to an excessively high content of the high refractive index component. Therefore, mass ratio (WO)₃)/(TiO₂+ZrO₂+Nb₂O₅+Ta₂O₅+WO₃) The upper limit is preferably 0.22, more preferably 0.20, still more preferably 0.10, and most preferably 0.08.

The MgO component, CaO component, SrO component and BaO component are optional components which can improve the meltability of the glass raw material and the devitrification resistance of the glass when the content exceeds 0%.

On the other hand, by setting the respective contents of the BaO component, CaO component and SrO component to 15.0% or less and/or setting the content of the MgO component to 10.0% or less, it is possible to suppress a decrease in refractive index and a decrease in devitrification resistance caused by excessively high contents of these components. Therefore, the respective contents of the BaO component, CaO component and SrO component are preferably 15.0% or more, more preferably 10.0% or more, and still more preferably 5.0% or more. Therefore, the upper limit of the content of the MgO component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.

MgO component, CaO component, SrO component and BaO component, MgCO can be used as the raw material₃、MgF₂、CaCO₃、CaF₂、Sr(NO₃)₂、SrF₂、BaCO₃、Ba(NO₃)₂、BaF₂And the like.

The sum of the contents (sum of mass) of the RO components is preferably 25.0% or less, wherein R is at least one selected from the group consisting of Mg, Ca, Sr and Ba. Accordingly, it is possible to suppress a decrease in the refractive index and resistance to devitrification of the glass due to an excessively high content of the RO component. Therefore, the sum of the RO components is preferably set to 25.0% by mass or more, more preferably 15.0% by mass or more, still more preferably 10.0% by mass or more, and still more preferably 5.0% by mass or more.

Li₂O component and Na₂Component O and K₂O component and Cs₂The O component is an optional component which improves the meltability of the glass and lowers the glass transition temperature when the content exceeds 0%. Wherein Na₂Component O and K₂O component and Cs₂The O component is also a component which can improve the devitrification resistance of the glass. Here, by making Li₂O component and Na₂Component O and K₂O component and Cs₂When the content of each of the O components is 10.0% or less, the refractive index of the glass is hardly lowered and devitrification resistance can be improved. Thus, Li₂O component and Na₂Component O and K₂O component and Cs₂The upper limit of the content of the O component is preferably 10.0%, more preferably 8.0%, and still more preferably 5.0%.

In particular, by reacting Li₂When the content of the O component is 3.0% or less, the viscosity of the glass can be increased, and therefore, the striae of the glass can be reduced. Therefore, Li is effective in reducing striae of the glass₂The content of the O component is preferably 3.0% or more, more preferably 1.0% or more, and still more preferably 0.3% or more.

Li₂O component and Na₂Component O and K₂O component and Cs₂O component, Li being used as a raw material₂CO₃、LiNO₃、Li₂CO₃、NaNO₃、NaF、Na₂SiF₆、K₂CO₃、KNO₃、KF、KHF₂、K₂SiF₆、Cs₂CO₃、CsNO₃And the like.

Rn₂The sum of the contents of O components is preferably 15.0% or less, where Rn is at least one selected from the group consisting of Li, Na, K and Cs. Accordingly, the decrease in the refractive index of the glass can be suppressed, and resistance to devitrification can be improved. Thus, Rn₂The sum of the O components is preferably 15.0% by mass or more, more preferably 10.0% by mass or more, and still more preferably 5.0% by mass or more.

P₂O₅The component (b) is an optional component which can improve the devitrification resistance of the glass when the content exceeds 0%. In particular, by reacting P₂O₅When the content of the component (B) is 10.0% or less, the chemical durability, particularly the water resistance of the glass can be suppressed from lowering. Thus, P₂O₅The upper limit of the content of the component (B) is preferably 10.0%, more preferablyThe upper limit of (1) is 5.0%, and more preferably 3.0%.

P₂O₅Component (B), Al (PO) can be used as a raw material₃)₃、Ca(PO₃)₂、Ba(PO₃)₂、BPO₄、H₃PO₄And the like.

GeO₂The component (b) is an optional component which can increase the refractive index of the glass and improve the devitrification resistance when the content exceeds 0%. However, due to GeO₂The raw materials are expensive, and if the amount of the raw materials is large, the material cost is increased, so that the reduction of Gd is offset₂O₃Component (A) and Ta₂O₅The components and the like, and the cost reduction effect. Thus, GeO₂The content of the component (B) is preferably 10.0% or more, more preferably 5.0% or more, still more preferably 1.0% or more, and still more preferably not contained.

GeO₂Ingredient GeO may be used as the raw material₂And the like.

ZrO₂When the content of the component (b) exceeds 0%, the glass can have a high refractive index and a low dispersion, and the resistance to devitrification can be improved. Thus, ZrO₂The content of the component (B) is preferably more than 0%, more preferably 1.0% or less, and still more preferably 3.0% or less.

On the other hand, by using ZrO₂The content of the component (A) is 15.0% or less, and ZrO due to the component (A) can be suppressed₂The decrease in devitrification resistance of the glass caused by an excessively high content of the component. Thus, ZrO₂The upper limit of the content of component (B) is preferably 15.0%, more preferably 10.0%, still more preferably 8.0%.

ZrO₂Component (b) ZrO can be used as a raw material₂、ZrF₄And the like.

The ZnO component is an optional component which can improve chemical durability while maintaining a desired refractive index and abbe number when the content exceeds 0%. In addition, since the material cost of the glass is reduced, it is possible to manufacture optical glass at a lower cost. Therefore, the content of the ZnO component is preferably more than 0%, more preferably 3.0% or less, still more preferably 5.0% or less, and most preferably 6.5% or less.

On the other hand, by setting the content of the ZnO component to 20.0% or less, the decrease in the refractive index and resistance to devitrification of the glass can be suppressed. In addition, the viscosity of the molten glass can be increased, and thus, the occurrence of glass streaks can be reduced. Therefore, the content of the ZnO component is preferably 20.0% or more, more preferably 18.0% or more, still more preferably 15.0% or more, and still more preferably 10.0% or more.

ZnO component, ZnO or ZnF can be used as the raw material₂And the like.

Al₂O₃Component (A) and Ga₂O₃When the content of the component (b) exceeds 0%, the chemical durability of the glass and the devitrification resistance of the glass can be improved.

On the other hand, by using Al₂O₃Component (A) and Ga₂O₃When the content of each component is 10.0% or less, the deterioration of devitrification resistance of the glass due to an excessively high content thereof can be suppressed. Thus, Al₂O₃Component (A) and Ga₂O₃The upper limit of the content of each component is preferably 10.0%, more preferably 5.0%, and still more preferably 3.0%.

Al₂O₃Component (A) and Ga₂O₃Component (C), Al can be used as a raw material₂O₃、Al(OH)₃、AlF₃、Ga₂O₃、Ga(OH)₃And the like.

Bi₂O₃The component (c) is an arbitrary component which can increase the refractive index and lower the glass transition temperature when the content exceeds 0%.

On the other hand, by using Bi₂O₃The content of the components is below 10.0%The devitrification resistance of the glass is high, and the dyeing of the glass can be reduced and the visible light transmittance can be improved. Thus, Bi₂O₃The upper limit of the content of the component (B) is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%.

Bi₂O₃Component (B) Bi can be used as a raw material₂O₃And the like.

TeO₂The component (c) is an arbitrary component which can increase the refractive index and lower the glass transition temperature when the content exceeds 0%.

However, TeO₂When a platinum crucible and a melting tank in which a portion in contact with molten glass is formed of platinum are used to melt glass raw materials, there is a problem that the raw materials can be alloyed with platinum. Thus, TeO₂The content of the component (B) is preferably 5.0% or more, more preferably 3.0% or more, still more preferably less than 1.0% or more, and still more preferably not contained.

TeO₂Component (C), TeO can be used as a raw material₂And the like.

SnO₂The component (C) is an optional component which can reduce the oxidation of the molten glass to make it clear and can improve the visible light transmittance of the glass when the content exceeds 0%.

On the other hand, by reacting SnO₂The content of the component is less than 1.0%, and the dyeing of the glass and the devitrification of the glass caused by the reduction of the molten glass can be reduced. In addition, SnO can be reduced₂The alloying of the components with the melting equipment (particularly noble metals such as Pt) makes it possible to achieve a longer service life of the melting equipment. Thus, SnO₂The content of the component (B) is preferably 1.0% or more, more preferably 0.7% or more, and still more preferably 0.5% or more.

SnO₂Component (C), SnO and SnO may be used as raw materials₂、SnF₂、SnF₄And the like.

Sb₂O₃When the content of the component (A) exceeds 0%, the component (B) may beTo defoam the molten glass. Sb₂O₃The component (B) is relative to the other components except Sb₂O₃The components other than the components are calculated by mass%.

On the other hand, if Sb is Sb₂O₃Too high content of (b) may result in a decrease in transmittance in a short wavelength region of the visible light region. Thus, Sb₂O₃The content of the component (B) is preferably 1.0% or more, more preferably 0.7% or more, and still more preferably 0.5% or more.

Sb₂O₃Component (C), Sb can be used as a raw material₂O₃、Sb₂O₅、Na₂H₂Sb₂O₇·5H₂O, and the like.

The component for clarifying and degassing the glass is not limited to Sb₂O₃As the component (b), a refining agent and a defoaming agent, or a combination thereof, which are well known in the glass production field, may be used.

< ingredients that should not be contained >

Next, components that should not be contained in the optical glass of the present invention and preferred components that are not contained therein will be described.

The other components may be added as needed within a range not to deteriorate the characteristics of the glass of the present invention. However, since each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, has a characteristic that the glass is dyed even when a small amount of each component is contained singly or in a mixture, and absorbs a specific wavelength in the visible region, it is not actually preferable particularly for optical glass using a wavelength in the visible region.

Lead compounds such As PbO and As₂O₃The arsenic compound is a component having a high environmental load, and therefore is not contained in practice, that is, is not contained uniformly except for inevitable mixing.

Further, each component of Th, Cd, Tl, Os, Be and Se tends to Be limited in use as a harmful chemical in recent years, and environmental protection measures are required not only in the production process of glass but also in the treatment process and the treatment up to the product production. Therefore, when importance is attached to the influence on the environment, it is preferable that these components are not actually contained.

The glass component of the present invention has a composition expressed by mol% of each component present in the glass component satisfying each characteristic required in the present invention, and the composition is expressed not directly by mol% but by mass% of the total mass of the glass in terms of oxides of the composition.

B₂O₃2.0 to 55.0 mol% of a component, and

La₂O₃the component (a) is 5.0 to 30.0 mol%, and

Y₂O₃the component(s) is (are) 0 to 20.0 mol%,

Gd₂O₃the component(s) is (are) 0 to 20.0 mol%,

Yb₂O₃the component(s) is (are) 0 to 10.0 mol%,

Ta₂O₅the component(s) is (are) 0 to 10.0 mol%,

WO₃the component(s) is (are) 0 to 20.0 mol%,

Nb₂O₅the component(s) is (are) 0 to 15.0 mol%,

TiO₂the component(s) is (are) 0 to 40.0 mol%,

SiO₂the component(s) is (are) 0 to 50.0 mol%,

MgO component in an amount of 0 to 50.0 mol%,

CaO component in an amount of 0 to 40.0 mol%,

0 to 30.0 mol% of SrO,

BaO component is 0-35.0 mol%,

Li₂0 to 30.0 mol% of an O component,

Na₂0 to 25.0 mol% of an O component,

K₂0 to 20.0 mol% of an O component,

Cs₂0 to 10.0 mol% of an O component,

P₂O₅the component(s) is (are) 0 to 15.0 mol%,

GeO₂the component(s) is (are) 0 to 10.0 mol%,

ZrO₂the component(s) is (are) 0 to 20.0 mol%,

0 to 50.0 mol% of ZnO,

Al₂O₃the component(s) is (are) 0 to 20.0 mol%,

Ga₂O₃the component(s) is (are) 0 to 10.0 mol%,

Bi₂O₃the component(s) is (are) 0 to 10.0 mol%,

TeO₂the component(s) is (are) 0 to 20.0 mol%,

SnO₂0 to 0.3 mol% of a component or

Sb₂O₃The component is0 to 0.5 mol%.

[ production method ]

The optical glass of the present invention is produced, for example, as follows. That is, the raw materials are uniformly mixed so that the contents of the components are within a predetermined range, the mixture is put into a platinum crucible, melted in an electric furnace at a temperature of 1100 to 1500 ℃ for 2 to 5 hours according to the melting difficulty of the glass composition, uniformly stirred, cooled to an appropriate temperature, poured into a mold, and slowly cooled, thereby manufacturing the glass.

[ physical Properties ]

The optical glass of the present invention preferably has a high refractive index and a high abbe number (low dispersion). In particular, the refractive index (nd) of the optical glass of the present invention is preferably 1.85, more preferably 1.87, still more preferably 1.88. The upper limit of the refractive index is preferably 2.20, more preferably 2.15, and further preferably 2.10. The abbe number (ν d) of the optical glass of the present invention is preferably 30 as the lower limit, more preferably 32 as the lower limit, further preferably 33 as the lower limit, further preferably 34 as the lower limit, further preferably 50 as the upper limit, further preferably 45 as the upper limit, further preferably 40 as the upper limit, and most preferably less than 38 as the upper limit.

Since the refractive index is high, a large amount of light refraction can be obtained even when the optical element is required to be thin. In addition, since the chromatic dispersion is low, even in a single lens, the shift of the focal point (chromatic aberration) due to the wavelength of light is reduced. Further, since having such low dispersion, for example, in combination with an optical element having high dispersion (low abbe number), higher imaging characteristics can be achieved.

Therefore, the optical glass of the present invention is useful for optical design, and in particular, not only can realize high imaging characteristics and the like and miniaturization of an optical system, but also can expand the degree of freedom of optical design.

In addition, the optical glass of the present invention is preferably small in specific gravity. More specifically, the optical glass of the present invention has a specific gravity of 5.00 (g/cm)³) The following. Accordingly, since the optical element and the optical instrument using the optical element can be reduced in weight, it is possible to help achieve weight reduction of the optical instrument. Therefore, the specific gravity of the optical glass of the present invention is preferably 5.00 as the upper limit, more preferably 4.95 as the upper limit, and still more preferably 4.90 as the upper limit. The specific gravity of the optical glass of the present invention is generally 3.00 or more, more specifically 3.50 or more, and still more specifically 4.00 or more.

The specific gravity of the optical glass of the present invention is measured based on "method for measuring specific gravity of optical glass" of Japan optical glass Industrial Association Standard JOGIS 05-1975.

The optical glass of the present invention has a high transmittance of visible light, particularly, a transmittance of light having a short wavelength side in the visible light, and thus is preferably less colored.

In particular, in the optical glass of the present invention, the spectral transmittance in a sample having a thickness of 10mm shows a wavelength (. lamda.) of 80%₈₀) The upper limit is preferably 520nm, more preferably 510nm, still more preferablyAn upper limit of 500nm is desirable.

In addition, in the optical glass of the present invention, the spectral transmittance shows a wavelength (. lamda.) of 70% in a sample having a thickness of 10mm₇₀) The upper limit is preferably 480nm, more preferably 450nm, and still more preferably 430 nm.

In addition, in the optical glass of the present invention, the spectral transmittance shows the shortest wavelength (λ) of 5% in a sample having a thickness of 10mm₅) The upper limit is preferably 440nm, more preferably 420nm, still more preferably 400nm, and still more preferably 380 nm.

Accordingly, the absorption edge of the glass is positioned in the vicinity of the ultraviolet region, and the transparency of the glass to visible light is improved, so that the optical glass can be preferably applied to an optical element that transmits light, such as a lens.

[ glass Molding and optical element ]

The glass molded body can be produced by a method of polishing or a method of press molding such as reheat press molding and precision press molding, for example, in addition to the produced optical glass. That is, the glass molded body can be produced by subjecting the optical glass to mechanical processing such as grinding and polishing, or by subjecting a preform produced from the optical glass to reheat press molding and then to polishing treatment, or by subjecting a preform produced by performing polishing treatment and a preform formed by float molding or the like, which is well known. The method for producing the glass shaped article is not limited to these methods.

Thus, the glass molded body formed of the optical glass of the present invention is useful for various optical elements and optical designs, and is particularly preferably used for optical elements such as lenses and prisms. Accordingly, a glass molded body having a large diameter can be formed, and therefore, not only can an optical element be increased in size, but also when used in an optical device such as a camera or a projector, high-definition and high-precision imaging characteristics and projection characteristics can be realized.

[ examples ] A method for producing a compound

Tables 1 to 4 show the compositions of examples (nos. 1 to 31) and comparative example (No. a) of the present invention, and the wavelengths (λ) at which the refractive index (nd), abbe number (ν d), and spectral transmittance of these glasses were 5%, 70%, and 80%₅、λ₇₀、λ₈₀) And, specific gravity results. In addition, the following embodiments are always for the purpose of illustration, and are not limited to these embodiments.

The glasses of examples and comparative examples of the present invention were produced by selecting high-purity raw materials used for general optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, metaphosphoric acid compounds, etc. corresponding to the respective component raw materials, weighing and uniformly mixing the raw materials at the composition ratios of the respective examples shown in the table, putting the raw materials into a platinum crucible, melting the mixture in an electric furnace at a temperature ranging from 1100 ℃ to 1500 ℃ for 2 to 5 hours according to the degree of difficulty of melting the glass composition, stirring the mixture uniformly, pouring the mixture into a mold, and slowly cooling the mixture.

The refractive index and Abbe number of the glasses of examples and comparative examples were measured in accordance with Japanese optical Nitri Industrial Standard JOGIS 01-2003.

The transmittance of the glasses of examples and comparative examples was measured in accordance with the japanese optical glass agency standard JOGIS 02. In the present invention, the degree and the absence of dyeing of the glass are determined by measuring the transmittance of the glass. Specifically, a spectral transmittance at 200 to 800nm is measured for a polished surface of 10. + -. 0.1mm thickness by JIS Z8722 to determine λ₅(wavelength at 5% transmittance), λ₇₀(wavelength at 70% transmittance) and λ₈₀(wavelength at which the transmittance is 80%).

The specific gravities of the glasses of examples and comparative examples were measured according to "method for measuring specific gravity of optical glass" of Japan optical glass Industrial Association Standard JOGIS 05-1975.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

The optical glasses of the examples of the present invention all had specific gravities of 5.00 or less. On the other hand, the glass of the comparative example had a specific gravity of more than 5.00.

Therefore, it is clear that the optical glass of the examples of the present invention has a lower specific gravity than the glass of the comparative example.

Further, the optical glass of the embodiment of the present invention, λ₈₀(wavelength at which the transmittance is 80%) is 520nm or less, more specifically 500nm or less. In addition, λ₇₀(wavelength at which the transmittance is 70%) is 480nm or less, more specifically 430nm or less. Further, the optical glass of the embodiment of the present invention, λ₅(wavelength at 5% transmittance) is 440nm or less, more specifically 380nm or less.

The optical glasses according to the examples of the present invention have a refractive index (nd) of 1.85 or more, more specifically 1.88 or more, and a refractive index of 2.20 or less, more specifically 2.00 or less, within the required range.

In the optical glass of the examples of the present invention, the abbe number (ν d) is 30 or more, more specifically 33 or more, and the abbe number is 50 or less, more specifically 45 or less, which are all within the required range.

Therefore, the optical glass according to the embodiment of the present invention can be produced at a low cost while having a refractive index and an abbe number within the required ranges, has high devitrification resistance, is less colored, and has a small specific gravity.

Further, using the optical glass of the example of the present invention, a glass block was formed, and the glass block was ground and polished to be processed into the shape of a lens and a preform. As a result, various shapes of lenses and preforms can be stably manufactured.

Although the present invention has been specifically described above for the purpose of examples, the present embodiment is always for the purpose of examples only, and various modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. An optical glass comprising B in an amount of mass% calculated on the basis of the oxide of the composition₂O₃5.0 to 30.0% of La₂O₃30.0 to 60.0%, WO₃The component is 0.1-5.0%, ₃ ₂mass ratio of oxide reference (WO)/(TiO +) ₂ ₂ ₅ ₂ ₅ ₃ZrO + NbO + TaO + WO) is 0.03 to 0.22 inclusive,sum of oxide-based masses (ZrO)₂+Nb₂O₅+Ta₂O₅+WO₃) 7.0% or less, a refractive index nd of 1.85 or more, an Abbe's number vd of 30 or more, and a specific gravity of 5.00 or less.

2. The optical glass according to claim 1, wherein the glass composition is calculated as mass% in terms of oxide,

Y₂O₃the component(s) is (are) 0 to 20.0%,

Gd₂O₃the component(s) is (are) 0 to 10.0%,

Yb₂O₃the component is 0-15.0%.

3. The optical glass according to claim 1 or 2, wherein the glass composition is characterized by containing, in terms of oxides, the following components in percentage by mass,

SiO₂the component is 0-15.0%,

TiO₂the component is 0-30.0%,

ZrO₂the components are 0 to 4.850 percent,

0 to 20.0 percent of ZnO,

MgO component of 0 to 10.0%,

CaO component is 0-15.0%,

0 to 15.0% of SrO,

BaO content is 0-15.0%,

Li₂0 to 10.0% of an O component,

Na₂0 to 10.0% of an O component,

K₂0 to 10.0% of an O component,

Ta₂O₅the component(s) is (are) 0 to 5.0%,

Nb₂O₅the component(s) is (are) 0 to 5.0%,

P₂O₅the component(s) is (are) 0 to 10.0%,

GeO₂the component(s) is (are) 0 to 10.0%,

Al₂O₃the component(s) is (are) 0 to 10.0%,

Ga₂O₃the component(s) is (are) 0 to 10.0%,

Bi₂O₃the component(s) is (are) 0 to 10.0%,

TeO₂0 to 5.0% of a component, and

SnO₂the component(s) is (are) 0 to 1.0%,

4. The optical glass according to claim 1, wherein the glass composition is characterized in that, in mass% on an oxide basis,

Ln₂O₃the sum of the mass of the components is 45.0-70.0%, wherein Ln is more than 1 selected from the group consisting of La, Gd, Y and Yb; rn₂The sum of the mass of the O components is 0-15.0%Wherein Rn represents 1 or more selected from the group consisting of Li, Na and K; the sum of the RO components is0 to 25.0% by mass, wherein R is at least 1 selected from the group consisting of Mg, Ca, Sr and Ba.

5. The optical glass according to claim 1, wherein λ is a wavelength at which the spectral transmittance is 70%₇₀Below 480 nm.

6. An optical element comprising the optical glass according to claim 1.

7. A preform comprising the optical glass according to claim 1 and used for polishing and/or precision press-molding.

8. An optical element, characterized in that the preform of claim 7 is precision press worked.