Optical glass, prefabricated member and optical element

Abstract

The present invention can obtain an optical glass having a small partial dispersion ratio ([theta] g, F) and a refractive index (nd) and an Abbe number ([nu] d) within required ranges. The optical glass contains, in mass%, 10.0 to 70.0% of an SiO2 component, 1.0 to 50.0% of an Nb2O5 component, and 1.0 to 30.0% of an Na2O component, and has a refractive index (nd) of 1.62 to 1.75 (inclusive), an Abbe number ([nu] d) of 30 to 42 (inclusive), and a partial dispersion ratio ([theta] g, F) of 0.594 or less.

Description

Technical Field

[0001] The invention relates to optical glass, a preform and an optical element. Background Art

[0002] Optical systems such as digital cameras and video cameras have a phenomenon called color fringing to a greater or lesser extent. This aberration is divided into monochromatic aberration and chromatic aberration, and chromatic aberration in particular depends largely on the material properties of the lens used in the optical system.

[0003] Usually, chromatic aberration is corrected by combining a low-dispersion convex lens and a high-dispersion concave lens, but this combination can only correct aberrations in the red and green regions, while aberrations in the blue region remain. This aberration in the blue region that cannot be removed is called the secondary spectrum. To correct the secondary spectrum, it is necessary to consider the trend of the g line (435.835nm) in the blue region when performing optical design. At this time, the partial dispersion ratio (θg, F) ​​is used as an indicator of optical characteristics that has attracted much attention in optical design. In the above-mentioned optical system that combines low-dispersion lenses and high-dispersion lenses, the secondary spectrum is well corrected by using an optical material with a larger partial dispersion ratio (θg, F) ​​in the lens on the low-dispersion side and an optical material with a smaller partial dispersion ratio (θg, F) ​​in the lens on the high-dispersion side.

[0004] The partial dispersion ratio (θg, F) ​​is expressed by the following formula (1).

[0005] θg,F=(n g -n F ) / (n F -n C )……(1)

[0006] In optical glass, the partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ) have a roughly linear relationship. The straight line representing this relationship is plotted with the partial dispersion ratio (θg, F) ​​as the vertical axis and the Abbe number (ν d ) is the horizontal axis of the rectangular coordinate system, and a straight line connecting two points plotting the partial dispersion ratio and Abbe number of NSL7 and PBM2 is used to represent it, which is called the standard line (refer to Figure 1 The standard glass used as the reference for the standard line varies depending on the optical glass manufacturer, but each manufacturer uses the same inclination and intercept for definition (NSL7 and PBM2 are optical glasses manufactured by Ohara Co., Ltd., and the Abbe number (ν d ) is 36.3, the partial dispersion ratio (θg, F) ​​is 0.5828, and the Abbe number (ν d) is 60.5, and the partial dispersion ratio (θg, F) ​​is 0.5436. ).

[0007] Here, as the Abbe number (ν d ) glass, such as the optical glass described in Patent Documents 1 and 2, is widely known.

[0008] [Patent Document 1] Japanese Patent Document Unexamined Patent Publication No. 2002-029777

[0009] [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-239478

[0010] Technical problem to be solved by the invention

[0011] However, the glass disclosed in Patent Document 1 has a relatively small partial dispersion ratio and is not sufficient to be used as a lens for correcting the secondary spectrum. In addition, although the glass disclosed in Patent Document 2 has a relatively small partial dispersion ratio, it has a large Abbe number, so a glass with a smaller Abbe number is needed.

[0012] The present invention is made in view of the above problems, and its object is to obtain a refractive index (n d ) and the Abbe number (ν d ) are within the required range and the partial dispersion ratio (θg, F) ​​is small. Summary of the invention

[0013] The inventors of the present invention have repeatedly conducted in-depth experiments and studies in order to solve the above-mentioned problems, and as a result, have discovered that in a glass containing SiO2 and Nb2O5 components, a glass having a high refractive index within the required range as well as a low Abbe number (high dispersion) and a low partial dispersion ratio can be obtained, thereby completing the present invention.

[0014] Specifically, the present invention provides the following optical glass.

[0015] (1) An optical glass characterized in that, calculated by mass %,

[0016] Contains 10.0-70.0% SiO2.

[0017] The Nb2O5 content is 1.0 to 50.0%, and

[0018] The Na2O content is 1.0-30.0%,

[0019] Furthermore, it has a refractive index (n d ),

[0020] Abbe number (ν 30 or more and less than 42 d),

[0021] Partial dispersion ratio (θg, F) ​​below 0.594.

[0022] (2) The optical glass according to (1) above, wherein the content of B2O3 is 25.0% or less, calculated by mass%.

[0023] (3) The optical glass according to (1) or (2) above, characterized in that the mass ratio (Li2O+Na2O) /

[0024] (ZrO2) is greater than 0.50.

[0025] (4) The optical glass according to any one of (1) to (3) above, wherein the content of Li2O component is 20.0% or less, calculated by mass%.

[0026] (5) The optical glass according to any one of (1) to (4) above, wherein the mass ratio (SiO2) / (SiO2+B2O3) is 0.50 or more.

[0027] (6) The optical glass according to any one of (1) to (5) above, wherein the mass ratio (SiO2) / (SiO2+B2O3) is 0.95 or less.

[0028] (7) The optical glass according to any one of (1) to (6) above, wherein the content of ZrO2 is 25.0% or less, calculated by mass%.

[0029] (8) The optical glass according to any one of (1) to (7) above, wherein, calculated by mass %,

[0030] K2O content is 0-20.0%,

[0031] TiO2 content is 0~20.0%,

[0032] MgO content is 0-10.0%,

[0033] The CaO content is 0 to 10.0%,

[0034] The SrO content is 0 to 10.0%,

[0035] BaO content is 0 to 20.0%,

[0036] Ta2O5 content is 0~10.0%,

[0037] La2O3 content is 0~10.0%,

[0038] Gd2O3 content is 0~10.0%,

[0039] Y2O3 content is 0~20.0%,

[0040] The Yb2O3 component is 0 to 10.0%.

[0041] P2O5 content is 0~10.0%,

[0042] GeO2 content is 0~10.0%,

[0043] Al2O3 content is 0~15.0%,

[0044] Ga2O3 content is 0~10.0%,

[0045] WO3 content is 0~10.0%,

[0046] Bi2O3 content is 0~10.0%,

[0047] The ZnO content is 0 to 30.0%,

[0048] TeO2 content is 0~15.0%,

[0049] SnO2 content is 0~5.0%,

[0050] The Sb2O3 component is 0 to 1.0%.

[0051] (9) The optical glass according to any one of (1) to (8) above, wherein the sum of the masses of Rn2O components is 1.0% to 30.0%, wherein Rn is one or more selected from the group consisting of Li, Na, and K.

[0052] (10) The optical glass according to any one of (1) to (9) above, wherein the mass ratio Li2O / Rn2O is greater than or equal to 0.01.

[0053] (11) The optical glass according to any one of (1) to (10) above, wherein the sum of the mass of RO components is less than 25.0%, wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba.

[0054] (12) An optical glass according to any one of (1) to (11) above, characterized in that the sum of the masses of Ln2O3 components is less than 20.0%, wherein Ln is one or more selected from the group consisting of Y, La, Gd, and Yb.

[0055] (13) A preform for polishing and / or precision stamping, characterized in that it is composed of the optical glass described in any one of (1) to (12) above.

[0056] (14) An optical element characterized by being composed of the optical glass described in any one of (1) to (12) above.

[0057] Effects of the Invention

[0058] According to the present invention, a refractive index (n d ) and the Abbe number (ν d ) are within the required range and the partial dispersion ratio (θg, F) ​​is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 The vertical axis is the partial dispersion ratio (θg, F) ​​and the vertical axis is the Abbe number (ν d ) is a schematic diagram of the standard line represented by the rectangular coordinates on the horizontal axis.

[0060] Figure 2 The partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ) relationship diagram.

[0061] Figure 3 is the refractive index (n) of the embodiment of the present invention d ) and the Abbe number (ν d ) relationship diagram. DETAILED DESCRIPTION

[0062] The optical glass of the present invention contains, by mass%, 10.0 to 70.0% of SiO2, 1.0 to 50.0% of Nb2O5, and 1.0 to 30.0% of Na2O, and has a refractive index (n) of not less than 1.62 and not more than 1.75. d ), Abbe number (ν d ) and a partial dispersion ratio (θg, F) ​​below 0.594.

[0063] In glass containing SiO2 and Nb2O5 components, glass having a high refractive index within the required range, a low Abbe number (high dispersion), and a low partial dispersion ratio can be obtained.

[0064] The first optical glass contains, by mass%, 10.0 to 70.0% of SiO2, 1.0 to 50.0% of Nb2O5, and 1.0 to 30.0% of Na2O, and the content of B2O3 is less than 20.0%, and has a refractive index (n) of not less than 1.62 and not more than 1.75. d), Abbe number (ν d ) and a partial dispersion ratio (θg, F) ​​below 0.594.

[0065] In glass containing SiO2 and Nb2O5, even if the content of B2O3 is reduced, glass having a high refractive index within the required range, a low Abbe number (high dispersion) and a low partial dispersion ratio can be obtained.

[0066] In addition, the second optical glass contains, by mass%, 10.0 to 70.0% of SiO2, 1.0 to 50.0% of Nb2O5, and 1.0 to 25.0% of Na2O, with a mass ratio (Li2O + Na2O) / (ZrO2) of 0.50 or more, and has a refractive index (n) of 1.64 to 1.70. d ), Abbe number (ν d ) and partial dispersion ratio (θg, F) ​​below 0.590.

[0067] In glass containing SiO2 and Nb2O5 components, especially when it contains Na2O and the mass ratio (Li2O+Na2O) / (ZrO2) is large, glass with a high refractive index within the required range, a low Abbe number (high dispersion) and a low partial dispersion ratio can be obtained.

[0068] In addition, the third optical glass contains, by mass%, 10.0 to 70.0% of SiO2, 1.0 to 50.0% of Nb2O5, 1.0 to 25.0% of Na2O, and 0.1 to 20.0% of Li2O, and has a refractive index (n) of not less than 1.62 and not more than 1.75. d ), Abbe number (ν d ) and a partial dispersion ratio (θg, F) ​​below 0.594.

[0069] In glass containing SiO2 and Nb2O5 components, especially in the case of containing Na2O and Li2O components, glass having a high refractive index within the required range, a low Abbe number (high dispersion) and a low partial dispersion ratio can be obtained.

[0070] Therefore, it is possible to obtain a material having not only the desired high refractive index (n d ) and low Abbe number (ν d ) and an optical glass with a small partial dispersion ratio (θg, F) ​​and which helps reduce chromatic aberration of the optical system.

[0071] In addition, an optical glass can be obtained which contributes to the weight reduction of optical equipment due to its low specific gravity, can be preferably used for applications that transmit visible light due to its high visible light transmittance, and can reduce the heating temperature during reheat pressing due to its low glass transition temperature.

[0072] Hereinafter, the embodiment of the optical glass of the present invention is specifically described, but the present invention is not subject to any limitation of the following embodiment, and within the scope of the purpose of the present invention, can be appropriately changed and implemented. In addition, for the part of explanation repetition, its explanation may be appropriately omitted sometimes, but the purpose of the invention is not limited.

[0073] [Glass composition]

[0074] The composition range of each component constituting the optical glass of the present invention is described below. In this specification, unless otherwise specified, the content of each component is expressed in mass % relative to the total mass of the glass in oxide conversion composition. Here, "oxide conversion composition" means that, assuming that the oxides, complex salts, metal fluorides, etc. used as raw materials for the glass composition components of the present invention are all decomposed and converted into oxides during melting, the total mass of the generated oxides is taken as 100 mass %, and the composition of each component contained in the glass is expressed.

[0075] <About essential ingredients and optional ingredients>

[0076] SiO2 is an essential component for promoting stable glass formation and reducing devitrification (formation of crystals) which is a defect of optical glass.

[0077] In particular, by making the SiO2 content 10.0% or more, devitrification can be reduced without significantly increasing the partial dispersion ratio. In addition, devitrification and coloration during reheating can be reduced accordingly. Therefore, the content of the SiO2 component is preferably 10.0% or more, more preferably greater than 20.0%, more preferably greater than 25.0%, more preferably greater than 30.0%, more preferably greater than 32.0%, more preferably greater than 34.0%, and more preferably greater than 35.0%.

[0078] On the other hand, by making the content of SiO2 component below 70.0%, the refractive index is difficult to decline and the required high refractive index can be obtained more easily, and the rise of the partial dispersion ratio can also be suppressed. In addition, the melting property of the glass raw material can also be suppressed to decline accordingly. Therefore, the content of SiO2 component is preferably below 70.0%, more preferably less than 60.0%, more preferably less than 50.0%, more preferably less than 45.0%, more preferably less than 43.0%, and more preferably less than 40.0%.

[0079] As the SiO2 component, SiO2, K2SiF6, Na2SiF6 and the like can be used as raw materials.

[0080] Nb2O5 is an essential component that can increase the refractive index of glass by making its content 1.0% or more, thereby reducing the Abbe number and partial dispersion ratio. Therefore, the content of Nb2O5 is preferably 1.0% or more, more preferably greater than 4.0%, more preferably greater than 7.0%, more preferably greater than 10.0%, more preferably greater than 15.0%, more preferably greater than 20.0%, more preferably greater than 23.0%, more preferably greater than 24.0%, more preferably greater than 25.0%, and more preferably greater than 26.0%.

[0081] On the other hand, by making the content of Nb2O5 component less than 50.0%, the material cost of glass can be reduced. In addition, the rise of melting temperature during glass manufacturing can be suppressed, and the devitrification caused by excessive content of Nb2O5 component can be reduced. Therefore, the content of Nb2O5 component is preferably less than 50.0%, more preferably less than 40.0%, more preferably less than 35.0%, more preferably less than 31.0%, and more preferably less than 30.0%.

[0082] As the Nb2O5 component, Nb2O5 and the like can be used as a raw material.

[0083] The Na2O component is an essential component that can reduce the partial dispersion ratio of the glass, improve the reheat pressing formability, reduce the glass transition temperature, and improve the meltability of the glass raw material by making its content 1.0% or more. Therefore, the content of the Na2O component is preferably 1.0% or more, more preferably greater than 3.0%, more preferably greater than 5.0%, more preferably greater than 6.0%, more preferably greater than 8.5%, more preferably greater than 10.0%, more preferably greater than 11.0%, and more preferably greater than 12.0%.

[0084] On the other hand, by making the content of the Na2O component 30.0% or less, the decrease in the refractive index of the glass can be suppressed, the chemical durability is unlikely to decrease, and the devitrification caused by excessive content can be reduced.

[0085] Therefore, the content of Na2O component is preferably 30.0% or less, more preferably 25.0% or less, more preferably less than 20.0%, more preferably less than 18.0%, more preferably less than 15.0%, and more preferably less than 13.0%.

[0086] As the Na2O component, Na2CO3, NaNO3, NaF, Na2SiF6 and the like can be used as raw materials.

[0087] The B2O3 component is an arbitrary component that can promote stable glass formation and reduce devitrification when the content exceeds 0%, and can also improve the meltability of glass raw materials. Therefore, the content of the B2O3 component is preferably greater than 0%, more preferably greater than 1.0%, more preferably greater than 3.0%, more preferably greater than 4.0%, more preferably greater than 5.5%, more preferably greater than 7.5%, and more preferably greater than 10.0%.

[0088] On the other hand, by making the content of B2O3 component less than 25.0%, the decrease of refractive index and the increase of Abbe number can be suppressed, and the increase of partial dispersion ratio can also be suppressed. Therefore, the content of B2O3 component is preferably less than 25.0%, more preferably less than 20.0%, more preferably less than 20.0%, more preferably less than 16.0%, more preferably less than 15.0%, and more preferably less than 12.5%.

[0089] As the B2O3 component, H3BO3, Na2B4O7, Na2B4O7·10H2O, BPO4 and the like can be used as raw materials.

[0090] The total ratio (mass ratio) of Li2O and Na2O to the content of ZrO2 is preferably above 0.50. This can improve the meltability of glass raw materials, reduce the devitrification of glass, and improve the reheat pressing formability of glass. Therefore, the mass ratio (Li2O+Na2O) / (ZrO2) is preferably 0.50 as the lower limit, more preferably 1.00 as the lower limit, more preferably 1.30 as the lower limit, more preferably 1.70 as the lower limit, and more preferably 1.78 as the lower limit.

[0091] On the other hand, the upper limit of the mass ratio (Li2O+Na2O) / (ZrO2) can be 1, but from the perspective of reducing the devitrification of the glass and improving the solubility of the glass raw materials, it is ideally less than 15.00, more ideally less than 12.00, and even more ideally less than 11.00.

[0092] The ZrO2 component is an arbitrary component that can increase the refractive index of the glass, reduce the Abbe number, reduce the partial dispersion ratio, and reduce devitrification when the content exceeds 0%. In addition, devitrification and coloring during reheating can be reduced accordingly. Therefore, the content of the ZrO2 component is preferably greater than 0%, more preferably greater than 1.0%, more preferably greater than 1.5%, more preferably greater than 3.0%, more preferably greater than 4.0%, more preferably greater than 5.0%, and more preferably greater than 7.0%.

[0093] On the other hand, by making the content of ZrO2 component below 25.0%, devitrification can be reduced and more uniform glass can be easily obtained. Therefore, the content of ZrO2 component is preferably below 25.0%, more preferably less than 20.0%, more preferably less than 18.0%, more preferably less than 16.0%, more preferably less than 15.0%, more preferably less than 13.0%, more preferably less than 10.0%, and more preferably less than 8.0%.

[0094] As the ZrO2 component, ZrO2, ZrF4 and the like can be used as raw materials.

[0095] The Li2O component is an arbitrary component that can reduce the partial dispersion ratio of the glass, improve the reheat pressing formability, reduce the glass transition temperature, and also improve the solubility of the glass raw materials when its content is greater than 0%. In particular, in the third optical glass, the Li2O component is an essential component that can reduce the partial dispersion ratio of the glass, improve the reheat pressing formability, reduce the glass transition temperature, and also improve the solubility of the glass raw materials by making its content greater than 0.1%. The content of the Li2O component in the optical glass of the present invention is preferably greater than 0.1%, more preferably greater than 0.5%, more preferably greater than 1.0%, more preferably greater than 2.0%, and more preferably may be greater than 2.5%.

[0096] On the other hand, by making the content of the Li2O component 20.0% or less, the decrease in the refractive index can be suppressed, the chemical durability is unlikely to decrease, and the devitrification caused by excessive content can be reduced.

[0097] Therefore, the content of Li2O component is preferably less than 20.0%, more preferably less than 10.0%, more preferably less than 8.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.4%.

[0098] As the Li2O component, Li2CO3, LiNO3, LiF and the like can be used as raw materials.

[0099] The K2O component is an arbitrary component which can lower the refractive index, improve the solubility of the glass raw material, and also lower the glass transition temperature when the content thereof exceeds 0%.

[0100] On the other hand, by making the content of K2O component 20.0% or less, the increase of partial dispersion ratio can be suppressed, devitrification can be reduced, and chemical durability can be made less likely to decrease. In addition, the reduction of re-hot press formability can be suppressed. Therefore, the content of K2O component is preferably 20.0% or less, more preferably 15.0% or less, more preferably less than 15.0%, more preferably less than 12.0%, more preferably less than 11.0%, more preferably less than 10.0%, more preferably less than 8.0%, more preferably less than 5.0%, and more preferably less than 3.0%.

[0101] As the K2O component, K2CO3, KNO3, KF, KHF2, K2SiF6 and the like can be used as raw materials.

[0102] The TiO2 component is an arbitrary component which can increase the refractive index, decrease the Abbe number, and reduce devitrification when the content thereof exceeds 0%.

[0103] On the other hand, by making the content of TiO2 component less than 20.0%, the coloring of glass can be reduced and the internal transmittance can be improved. In addition, it is difficult to increase the partial dispersion ratio, so it is easy to obtain the required low partial dispersion ratio. Therefore, the content of TiO2 component is preferably less than 20.0%, more preferably less than 15.0%, more preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, more preferably less than 1.0%, and more preferably less than 0.1%.

[0104] As the TiO2 component, TiO2 and the like can be used as a raw material.

[0105] The MgO component is an arbitrary component that can lower the melting point of glass when the content exceeds 0%.

[0106] On the other hand, by making the content of the MgO component 10.0% or less, the decrease in the refractive index and the increase in the Abbe number can be suppressed, and devitrification can also be reduced. Therefore, the content of the MgO component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, more preferably less than 1.0%, and more preferably less than 0.5%.

[0107] As the MgO component, MgO, MgCO 3 , MgF 2 , etc. can be used as a raw material.

[0108] The CaO component is an arbitrary component that can reduce the material cost of glass and reduce devitrification when the content exceeds 0% and can also improve the solubility of glass raw materials.

[0109] On the other hand, by making the content of the CaO component 10.0% or less, the decrease in the refractive index, the increase in the Abbe number, and the increase in the partial dispersion ratio can be suppressed, and devitrification can also be reduced. Therefore, the content of the CaO component is preferably 10.0% or less, more preferably less than 5.0%, more preferably less than 3.0%, more preferably less than 1.9%, and more preferably less than 0.5%.

[0110] As the CaO component, CaCO3, CaF2 and the like can be used as raw materials.

[0111] The SrO component is an arbitrary component which can reduce the devitrification of glass and increase the refractive index when the content thereof exceeds 0%.

[0112] In particular, by making the content of the SrO component less than 10.0%, not only the increase in the Abbe number can be suppressed, but also the decrease in chemical durability can be suppressed. Therefore, the content of the SrO component is preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0113] As the raw material of the SrO component, Sr(NO3)2, SrF2, etc. can be used.

[0114] BaO is an arbitrary component that can reduce devitrification, improve the refractive index and the meltability of glass raw materials when the content exceeds 0%, and can also reduce the cost of glass materials compared with other alkaline earth components. In addition, it is also a component that can suppress the reduction of reheat press formability.

[0115] On the other hand, by making the content of BaO component less than 20.0%, not only the increase of Abbe number can be suppressed, but also the decrease of chemical durability and devitrification can be suppressed. Therefore, the content of BaO component is preferably less than 20.0%, more preferably less than 15.0%, more preferably less than 10.0%, and more preferably less than 5.0%.

[0116] As the raw material of the BaO component, BaCO3, Ba(NO3)2, etc. can be used.

[0117] The Ta2O5 component is an arbitrary component which can increase the refractive index of the glass, reduce the partial dispersion ratio, and reduce the devitrification of the glass when the content thereof exceeds 0%.

[0118] On the other hand, by making the content of Ta2O5 component below 10.0%, the usage of rare mineral resource Ta2O5 component is reduced, and because glass is more easily melted at a lower temperature, the material cost and production cost of glass can be reduced. In addition, the devitrification of glass caused by excessive content of Ta2O5 component and the rise of Abbe number can be reduced accordingly. Therefore, the content of Ta2O5 component is preferably below 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, more preferably less than 1.0%, and more preferably less than 0.5%. In particular, from the perspective of reducing the material cost of glass, the content of Ta2O5 component can also be less than 0.1%.

[0119] Ta2O5 component, Ta2O5 etc. can be used as a raw material.

[0120] The La2O3 component, the Gd2O3 component, the Y2O3 component, and the Yb2O3 component are arbitrary components that can increase the refractive index of the glass and also reduce the partial dispersion ratio by making the content of at least any one of them exceed 0%.

[0121] On the other hand, by making the content of La2O3 component less than 10.0%, the increase of Abbe number can be suppressed, the specific gravity can be reduced, and devitrification can also be reduced. Therefore, the content of La2O3 component is preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0122] In addition, by making the content of Y2O3 component less than 20.0%, the increase of Abbe number can be suppressed, the specific gravity can be reduced, and devitrification can be reduced. Therefore, the content of Y2O3 component is preferably less than 20.0%, more preferably less than 10.0%, more preferably less than 5.0%, and more preferably less than 3.0%.

[0123] In addition, by making the contents of Gd2O3 and Yb2O3 components less than 10.0%, the increase of Abbe number can be suppressed, the specific gravity can be reduced, devitrification can be reduced, and the material cost can also be reduced. Therefore, the contents of Gd2O3 and Yb2O3 are preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0124] La2O3 component, Gd2O3 component, Y2O3 component and Yb2O3 component, as raw materials, La2O3, La(NO3)3·XH2O (X is an arbitrary integer), Y2O3, YF3, Gd2O3, GdF3, Yb2O3, etc. can be used.

[0125] The P2O5 component is an arbitrary component that can reduce the devitrification of glass when the content thereof exceeds 0%.

[0126] On the other hand, by making the content of P2O5 component less than 10.0%, devitrification caused by excessive content of P2O5 component can be reduced. Therefore, the content of P2O5 component is preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0127] The P2O5 component can be made of Al(PO3)3, Ca(PO3)2, Ba(PO3)2, BPO4, H3PO4, etc.

[0128] The GeO2 component is an arbitrary component which can increase the refractive index of glass and reduce devitrification when the content thereof exceeds 0%.

[0129] On the other hand, by making the content of GeO2 component less than 10.0%, the usage of the more expensive GeO2 component can be reduced, so the material cost of the glass can be reduced. Therefore, the content of GeO2 component is preferably less than 10.0%, more preferably less than 5.0%, and even more preferably less than 1.0%.

[0130] GeO2 component, GeO2 etc. can be used as a raw material.

[0131] The Al 2 O 3 component and the Ga 2 O 3 component are arbitrary components that can improve chemical durability and reduce devitrification of glass when the content of at least any one of them exceeds 0%.

[0132] On the other hand, by making the content of Al2O3 component less than 15.0%, devitrification caused by excessive content can be reduced. Therefore, the content of Al2O3 component is preferably less than 15.0%, more preferably less than 8.0%, more preferably less than 5.0%, and more preferably less than 3.0%.

[0133] On the other hand, by making the content of Ga2O3 component less than 10.0%, devitrification caused by excessive content can be reduced. Therefore, the content of Ga2O3 component is preferably less than 10.0%, more preferably less than 5.0%, and even more preferably less than 3.0%.

[0134] As the Al2O3 component and the Ga2O3 component, Al2O3, Al(OH)3, AlF3, Ga2O3, Ga(OH)3 and the like can be used as raw materials.

[0135] The WO3 component is an arbitrary component which can increase the refractive index and decrease the Abbe number to reduce the devitrification of the glass when the content thereof exceeds 0%, and can also improve the solubility of the glass raw material.

[0136] On the other hand, by making the content of WO3 component less than 10.0%, it is possible to make the partial dispersion ratio difficult to increase, and it is also possible to improve the internal transmittance by reducing the coloring of the glass. Therefore, the content of WO3 component is preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0137] As the WO3 component, WO3 or the like can be used as a raw material.

[0138] The Bi2O3 component is an arbitrary component which can increase the refractive index and decrease the Abbe number when the content thereof exceeds 0%, and can also decrease the glass transition temperature.

[0139] On the other hand, by making the content of Bi2O3 component less than 10.0%, it is difficult to increase the partial dispersion ratio, and it is also possible to improve the internal transmittance by reducing the coloring of the glass. Therefore, the content of Bi2O3 component is preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0140] Bi2O3 component, Bi2O3 etc. can be used as a raw material.

[0141] The ZnO component is an arbitrary component which can reduce the devitrification of glass, lower the partial dispersion ratio, and also lower the glass transition temperature when the content thereof exceeds 0%.

[0142] On the other hand, by making the content of ZnO component less than 30.0%, not only can the devitrification and coloring of glass during reheating be reduced, but also the chemical durability can be improved. Therefore, the content of ZnO component is preferably less than 30.0%, more preferably less than 20.0%, more preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, more preferably less than 2.0%, and more preferably less than 1.0%.

[0143] As the ZnO component, ZnO, ZnF2 and the like can be used as raw materials.

[0144] The TeO2 component is an arbitrary component that can increase the refractive index, reduce the partial dispersion ratio, and also reduce the glass transition temperature when the content thereof exceeds 0%.

[0145] On the other hand, by making the content of TeO2 component less than 15.0%, the coloring of glass can be reduced and the internal transmittance can be improved. In addition, by reducing the use of the more expensive TeO2 component, cheaper glass can be obtained. Therefore, the content of TeO2 component is preferably less than 15.0%, more preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0146] TeO2 component, TeO2 etc. can be used as a raw material.

[0147] The SnO2 component is an arbitrary component which can make the molten glass clear (defoam) and can also improve the visible light transmittance of the glass when the content thereof exceeds 0%.

[0148] On the other hand, by making the content of SnO2 component below 5.0%, it is difficult to cause the coloring of glass and the devitrification of glass caused by the reduction of molten glass. In addition, since the alloying of SnO2 component with melting equipment (especially precious metals such as Pt) can be reduced, a longer service life of the melting equipment can be achieved. Therefore, the content of SnO2 component is preferably below 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0149] SnO2 component can use SnO, SnO2, SnF2, SnF4 and the like as raw materials.

[0150] The Sb2O3 component is an arbitrary component that can make the glass clear when the content thereof exceeds 0%.

[0151] On the other hand, by making the content of Sb2O3 component below 1.0%, it is not easy to produce excessive foaming when the glass is melted, so it is difficult to alloy the Sb2O3 component with the melting equipment (especially precious metals such as Pt). Therefore, the content of Sb2O3 component is preferably 1.0% or less as the upper limit, more preferably less than 0.5% as the upper limit, and more preferably less than 0.1% as the upper limit. However, in the case of attaching importance to the impact of optical glass on the environment, Sb2O3 component may not be contained.

[0152] As the Sb2O3 component, Sb2O3, Sb2O5, Na2H2Sb2O7·5H2O and the like can be used as raw materials.

[0153] In addition, the component for clarifying the glass is not limited to the above-mentioned Sb2O3 component, and clarifiers well-known in the field of glass manufacturing, or combinations thereof can also be used.

[0154] Relative to the total amount of SiO2 component and B2O3 component, the ratio (mass ratio) of SiO2 component content can also be above 0.10. Accordingly, the rise of the Abbe number of glass can be suppressed. Therefore, the mass ratio (SiO2) / (SiO2+B2O3) is preferably 0.10 as the lower limit, more preferably 0.30 as the lower limit, more preferably 0.50 as the lower limit, more preferably 0.65 as the lower limit, and more preferably 0.75 as the lower limit.

[0155] On the other hand, the upper limit of the mass ratio (SiO2) / (SiO2+B2O3) can also be 1, but from the perspective of suppressing the increase in glass transition temperature, reducing the devitrification of glass, and improving the solubility of glass raw materials, it is ideally less than 1, more ideally less than 0.98, more ideally below 0.95, more ideally below 0.95, more ideally below 0.93, more ideally below 0.90, more ideally below 0.88, more ideally below 0.83, and more ideally below 0.80.

[0156] The sum (mass sum) of the contents of the Rn2O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is ideally 1.0% to 30.0%.

[0157] In particular, by making the sum of the masses above 1.0, the meltability of the glass raw material can be improved and the glass transition temperature can be lowered. Therefore, the total content of the Rn2O component is preferably above 1.0%, more preferably greater than 5.0%, more preferably greater than 10.0%, and more preferably also greater than 12.0%.

[0158] On the other hand, by making the sum of the masses below 30.0%, the refractive index of the glass is difficult to decrease, and the devitrification when the glass is formed can also be reduced. Therefore, the total content of the Rn2O component is preferably below 30.0%, more preferably less than 25.0%, more preferably less than 23.0%, more preferably less than 21.0%, more preferably less than 20.0%, and more preferably less than 18.0%.

[0159] The mass ratio Li2O / Rn2O is preferably 0.01 or more. This can reduce the partial dispersion ratio of the glass, improve the reheat pressing formability, and reduce the glass transition temperature. Therefore, the mass ratio Li2O / Rn2O is preferably 0.01 or more, more preferably greater than 0.05, more preferably greater than 0.10, and more preferably greater than 0.14.

[0160] On the other hand, the upper limit of the mass ratio Li2O / Rn2O is preferably 0.60, more preferably 0.50, and even more preferably 0.40 from the viewpoint of reducing the devitrification of the glass.

[0161] The sum of the contents (mass sum) of the RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably less than 25.0%. This can suppress the increase in the Abbe number and reduce the devitrification of the glass caused by excessive contents of these components. Therefore, the sum of the mass of the RO components is preferably less than 25.0%, more preferably less than 15.0%, more preferably less than 10.0%, more preferably less than 5.0%, and more preferably less than 2.0%.

[0162] The sum of the contents (mass sum) of the Ln2O3 components (wherein Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably less than 20.0%. This can reduce the devitrification of the glass, suppress the increase in the Abbe number, and reduce the material cost. Therefore, the sum of the mass of the Ln2O3 components is preferably less than 20.0%, more preferably less than 15.0%, more preferably less than 10.0%, more preferably less than 5.0%, more preferably less than 3.0%, and more preferably less than 1.0%.

[0163] <About ingredients that should not be contained>

[0164] Next, components that should not be contained in the optical glass of the present invention and components that are preferably not contained are described.

[0165] Other components can be added as needed within the range that does not damage the glass properties of the present invention. However, in addition to Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, various transition metal components such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo have the characteristics that the glass will be colored even if a small amount of each component is contained alone or in mixture, and absorb specific wavelengths in the visible region. Therefore, it is preferably not actually contained in optical glass using wavelengths in the visible region.

[0166] In addition, since lead compounds such as PbO and arsenic compounds such as As2O3 are components with a high environmental burden, it is best not to actually contain them, that is, it is best not to contain them at all except for unavoidable mixing.

[0167] In addition, the use of Th, Cd, Tl, Os, Be and Se has been restricted as hazardous chemical substances in recent years, and environmental protection measures are required not only in the production process of glass, but also in the processing process and the handling after productization. Therefore, if the impact on the environment is important, it is better not to contain these components.

[0168] [Manufacturing method]

[0169] The optical glass of the present invention is manufactured, for example, as follows. That is, the raw materials are uniformly mixed so that each component is within a predetermined content range, the manufactured mixture is placed in a platinum crucible, a quartz crucible or an alumina crucible for pre-melting, and then placed in a gold crucible, a platinum crucible, a platinum alloy crucible or an iridium crucible and melted at a temperature range of 1100 to 1400° C. for 3 to 5 hours, uniformly stirred and defoamed, etc., and then the temperature is lowered to 1000 to 1400° C. and finally stirred to remove streaks, and then poured into a mold and slowly cooled to manufacture.

[0170] At this time, it is more desirable to use a material with higher melting properties as the glass raw material. This can improve the glass production efficiency and reduce the production cost because it can be melted at a lower temperature and in a shorter time. In addition, it is easier to obtain less colored glass because it can reduce the volatilization of components and the reaction with the crucible, etc.

[0171] <Physical Properties>

[0172] The optical glass of the present invention has a high refractive index and an Abbe number within a predetermined range.

[0173] The refractive index (n d ), preferably 1.62 is the lower limit, more preferably 1.63 is the lower limit, more preferably 1.64 is the lower limit, and more preferably 1.65 is the lower limit. The upper limit of the refractive index is preferably 1.75, more preferably 1.74, more preferably 1.72, more preferably 1.70, and more preferably 1.68.

[0174] The Abbe number (ν d ), preferably 42 or less, more preferably 40 or less, more preferably 39 or less, and more preferably 38 or less. On the other hand, the Abbe number (ν d ), the lower limit is preferably 30, the lower limit is more preferably 32, the lower limit is more preferably 33, and the lower limit is even more preferably 34.

[0175] The optical glass of the present invention having such a refractive index and Abbe number is useful for optical design, and in particular, can not only achieve higher imaging characteristics and miniaturization of optical systems, but also expand the degree of freedom of optical design.

[0176] Here, the optical glass of the present invention has a refractive index (n d ) and the Abbe number (ν d ), the ideal is to satisfy (-0.012ν d +2.04)≦n d ≦(-0.012ν d +2.16). The glass of the specific composition of the present invention is obtained by adjusting the refractive index (n d ) and the Abbe number (ν d ) satisfies this relationship, it is possible to obtain glass that is less likely to lose clarity.

[0177] Therefore, in the optical glass of the present invention, the refractive index (n d ) and the Abbe number (ν d ), it is more ideal to satisfy n d ≧(-0.012ν d +2.04), it is more ideal to satisfy n d ≧(-0.012ν d +2.05), it is more ideal to satisfy n d ≧(-0.012ν d +2.06), and more ideally, it satisfies n d ≧(-0.012ν d +2.08).

[0178] On the other hand, in the optical glass of the present invention, the refractive index (n d ) and the Abbe number (ν d ), it is more ideal to satisfy n d ≦(-0.012ν d +2.16), and more ideally, it satisfies n d ≦(-0.012ν d +2.14), it is more ideal to satisfy n d ≦(-0.012ν d +2.13), it is more ideal to satisfy n d ≦(-0.012ν d +2.12).

[0179] The optical glass of the present invention has a relatively low partial dispersion ratio (θg, F).

[0180] More specifically, the upper limit of the partial dispersion ratio (θg, F) ​​of the optical glass of the present invention is preferably 0.594, more preferably 0.592, more preferably 0.590, and more preferably 0.588. The lower limit of the partial dispersion ratio (θg, F) ​​is preferably 0.570, more preferably 0.573, more preferably 0.575, more preferably 0.576, and more preferably 0.577.

[0181] In addition, the partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ), the ideal one is (-0.00162×ν d +0.630)≦(θg,F)≦(-0.00162×ν d +0.652).

[0182] According to this, since an optical glass having a low partial dispersion ratio (θg, F) ​​can be obtained, an optical element formed of the optical glass can contribute to reducing chromatic aberration of an optical system.

[0183] Therefore, in the optical glass of the present invention, the partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ), the ideal is to satisfy θg, F≧(-0.00162×ν d +0.630), and more ideally, θg, F≧(-0.00162×ν d +0.632), it is more ideal to satisfy θg, F ≧ (-0.00162 × ν d +0.634).

[0184] On the other hand, in the optical glass of the present invention, the partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ), the ideal is to satisfy θg, F ≦ (-0.00162 × ν d +0.652), and more ideally, θg, F≦(-0.00162×ν d +0.650), and more ideally, θg, F≦(-0.00162×ν d +0.648), and more ideally, θg, F≦(-0.00162×ν d +0.646), it is more ideal to satisfy θg, F ≦ (-0.00162 × ν d +0.643).

[0185] In addition, in the above partial dispersion ratio (θg, F) ​​and Abbe number (νd ) in the relationship between the two, by using a straight line with the same inclination as the standard line to define these relationships, it is shown that a glass with a smaller partial dispersion ratio (θg, F) ​​than ordinary glass can be obtained.

[0186] The optical glass of the present invention preferably has a smaller specific gravity. More specifically, the specific gravity of the optical glass of the present invention is 3.80 (g / cm 3 ) or less. Accordingly, since the mass of optical elements and optical instruments using the optical elements can be reduced, it can help to achieve lightweight optical instruments. Therefore, the specific gravity of the optical glass of the present invention is preferably 3.80 as the upper limit, more preferably 3.50 as the upper limit, more preferably 3.30 as the upper limit, more preferably 3.10 as the upper limit, and more preferably 3.00 as the upper limit. In addition, the specific gravity of the optical glass of the present invention is generally above 2.50, more specifically above 2.70, and more specifically above 2.80.

[0187] The specific gravity of the optical glass of the present invention is measured based on the Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method for measuring specific gravity of optical glass".

[0188] The optical glass of the present invention is preferably less colored.

[0189] In particular, the wavelength (λ5) at which the spectral transmittance of the optical glass of the present invention shows 5% in a sample having a thickness of 10 mm is preferably 400 nm or less, more preferably 380 nm or less, and even more preferably 350 nm or less.

[0190] In addition, the optical glass of the present invention has a spectral transmittance of 80% at a wavelength (λ 80 ), preferably below 450nm, more preferably below 420nm, and even more preferably below 400nm.

[0191] Accordingly, the absorption end of the glass will be located near the ultraviolet region, which improves the transparency of the glass in the visible region. Therefore, this optical glass can be preferably used as a material for optical elements such as lenses.

[0192] The optical glass of the present invention preferably has a glass transition temperature of 650°C or less. Accordingly, the glass softens at a lower temperature, so the glass can be molded at a lower temperature. In addition, the service life of the mold can be extended by reducing the oxidation of the mold used for compression molding. Therefore, the glass transition temperature of the optical glass of the present invention is preferably 650°C as the upper limit, more preferably 620°C as the upper limit, more preferably 600°C as the upper limit, more preferably 580°C as the upper limit, and more preferably 550°C as the upper limit.

[0193] Although the lower limit of the glass transition temperature of the optical glass of the present invention is not particularly limited, the glass transition temperature of the optical glass of the present invention is preferably 460°C, more preferably 480°C, and even more preferably 500°C.

[0194] The optical glass of the present invention preferably has a yield point (At) below 720°C. The yield point, like the glass transition temperature, is an indicator of the softening property of the glass, and is also an indicator of a temperature close to the press molding temperature. Therefore, by using glass with a yield point below 720°C, press molding can be performed at a lower temperature, so press molding can be performed more easily. Therefore, the yield point of the optical glass of the present invention is preferably 720°C as the upper limit, more preferably 700°C as the upper limit, more preferably 690°C as the upper limit, more preferably 680°C as the upper limit, more preferably 660°C as the upper limit, more preferably 650°C as the upper limit, and more preferably 630°C as the upper limit.

[0195] The deformation point of the optical glass of the present invention is not particularly limited, but is preferably 500°C, more preferably 530°C, and even more preferably 560°C.

[0196] The optical glass of the present invention preferably has a smaller average linear expansion coefficient (α). In particular, the average linear expansion coefficient of the optical glass of the present invention is preferably 150×10 －7 K －1 The upper limit is 120×10 －7 K －1 The upper limit is 115×10 －7 K －1 The upper limit is 110×10 －7 K －1 The upper limit is 100×10 －7 K －1As the upper limit. Accordingly, when the optical glass is stamped and formed using a forming mold, the total amount of expansion and contraction caused by the temperature change of the glass can be reduced. Therefore, the optical glass is difficult to break during stamping and the production efficiency of the optical element can be improved.

[0197] The optical glass of the present invention preferably has good reheat press moldability. More specifically, the optical glass of the present invention preferably does not become devitrified or opalescent even before and after a reheat test (drop mold test). Accordingly, since devitrification and coloration are unlikely to occur in a reheat test for simulating a reheat press molding process, the light transmittance of the glass is unlikely to be lost, and therefore the glass can be easily subjected to a reheat treatment representing a reheat press molding process. In other words, since optical elements with complex shapes can be manufactured by press molding, the manufacture of optical elements with relatively low manufacturing costs and relatively good production efficiency can be achieved.

[0198] Here, the reheating test (drop test) can be implemented by the following method, that is, a test piece of 15mm×15mm×30mm is placed on a concave refractory and put into an electric furnace for reheating, and is heated from room temperature to a temperature (the temperature of falling into the refractory) of 80℃~150℃ higher than the transformation temperature (Tg) of each sample after 150 minutes, and after keeping at this temperature for 30 minutes, it is cooled to room temperature and taken out of the furnace, and the opposite sides are polished to a thickness of 10mm so that it can be observed inside, and then the polished glass sample is observed with the naked eye.

[0199] In addition, the presence or absence of devitrification and opalescence before and after the reheating test (mold drop test) can be confirmed by, for example, the naked eye, and "no devitrification and opalescence" means that, for example, the transmittance of the test piece after the reheating test (mold drop test) to light (d-line) with a wavelength of 587.56nm divided by the transmittance of the test piece before the reheating test to the d-line is approximately greater than 0.80.

[0200] The optical glass of the present invention preferably has high chemical durability. More specifically, the optical glass of the present invention preferably has high water resistance and acid resistance. Accordingly, when the optical glass is polished, the atomization of the glass caused by the cleaning liquid and the polishing liquid is reduced, so the polishing process can be performed more easily.

[0201] The water resistance and acid resistance of optical glass refer to the chemical durability (water resistance, acid resistance) measured according to the Japan Optical Glass Industry Association standard "Measurement method for chemical durability of optical glass" JOGIS06-2008. The ideal value is 1 to 3, the more ideal value is 1 to 2, and the most ideal value is 1.

[0202] The optical glass of the present invention is preferably difficult to be devitrified during the manufacture of the glass. Accordingly, the reduction of transmittance caused by crystallization of the glass can be suppressed during the manufacture of the glass, so the optical glass can be preferably used in optical elements such as lenses that transmit visible light. In addition, as a standard indicating the degree of difficulty of devitrification during the manufacture of the glass, for example, a low liquidus temperature can be cited.

[0203] [Preforms and optical components]

[0204] Based on the manufactured optical glass, a glass molded body can be manufactured by using a compression molding method such as reheat pressing molding and precision stamping molding. That is, a preform for compression molding can be manufactured using optical glass, and the preform can be reheat pressed and then polished to manufacture a glass molded body, or a preform manufactured by polishing can be precision stamped to manufacture a glass molded body. In addition, the method of manufacturing a glass molded body is not limited to these methods.

[0205] The glass molded body manufactured in this way is useful for various optical elements, and is particularly preferably used for optical elements such as lenses and prisms. According to this, color fringing caused by chromatic aberration is reduced in the transmitted light of an optical system provided with the optical element. Therefore, when the optical element is used in a camera, the subject can be more accurately represented, and when the optical element is used in a projector, the desired image can be projected more clearly.

[0206] [Example]

[0207] The compositions and refractive index (n d ), Abbe number (ν d ), partial dispersion ratio (θg, F), spectral transmittance at 5% and 80% wavelength (λ5, λ 80 ), glass transition temperature (Tg), yield point (At), average linear expansion coefficient (α) and specific gravity are shown in Tables 1 to 8. Here, Examples (No.A1 to No.A27) can be used as examples of the first optical glass, Examples (No.B1 to No.B11) can be used as examples of the second optical glass, and Examples (No.C1 to No.C12) can also be used as examples of the third optical glass, but are not limited thereto. In addition, the following examples are always for the purpose of illustration and are not limited to these examples.

[0208] The glasses of the embodiments are all made of high-purity raw materials used in ordinary optical glasses, such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds, which are respectively equivalent to the raw materials of each component. They are weighed and evenly mixed according to the composition ratios of the embodiments shown in the table, and then put into a platinum crucible. Depending on the melting difficulty of the glass raw materials, they are melted in an electric furnace at a temperature range of 1100°C to 1400°C for 3 to 5 hours, stirred evenly and defoamed, etc., and the temperature is lowered to 1000 to 1400°C. After stirring evenly, the glass is poured into a mold and slowly cooled, thereby manufacturing the glass.

[0209] The refractive index of the glass of the embodiment (n d ), Abbe number (ν d ) and partial dispersion ratio (θg, F) ​​were measured in accordance with the Japan Optical Glass Industries Association Standard JOGIS01-2003.

[0210] And, according to the obtained refractive index (n d ) and the Abbe number (ν d ) value, in the relation (n d =-a×ν d +b), find the intercept b when the slope a is 0.012.

[0211] In addition, according to the obtained Abbe number (ν d ) and the value of the partial dispersion ratio (θg, F), in the relationship (θg, F = -a′×ν d + b′), find the intercept b′ when the slope a′ is 0.00162.

[0212] In addition, the glass used in this measurement was treated in an annealing furnace at a slow cooling rate of -25°C / hr.

[0213] The transmittance of the glass of the embodiment is measured according to the standard of Japan Optical Glass Industry Association JOGIS02. In addition, in the present invention, the coloration of the glass and its degree are obtained by measuring the transmittance of the glass. Specifically, the spectral transmittance of 200 to 800 nm is measured according to JIS Z8722 for a polished product with parallel opposite surfaces and a thickness of 10 ± 0.1 mm, and λ5 (the wavelength when the transmittance is 5%) and λ 80 (Wavelength at which the transmittance is 80%).

[0214] The glass transition temperature (Tg) and yield point (At) of the glass of the examples were determined from a thermal expansion curve obtained by measuring the relationship between temperature and extension of the sample in accordance with Japan Optical Glass Industries Association Standard JOGIS08-2003 "Method for measuring thermal expansion of optical glass".

[0215] The average linear expansion coefficient (α) of the glass of the example was determined at 100 to 300° C. in accordance with the Japan Optical Glass Industry Association Standard JOGIS08-2003 “Measurement method for thermal expansion of optical glass”.

[0216] The specific gravity of the glass of the examples was measured in accordance with the Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method for measuring specific gravity of optical glass".

[0217] Table 1

[0218]

[0219] Table 2

[0220]

[0221] Table 3

[0222]

[0223] Table 4

[0224]

[0225] Table 5

[0226]

[0227] Table 6

[0228]

[0229] Table 7

[0230]

[0231] Table 8

[0232]

[0233] As shown in these tables, the partial dispersion ratio (θg, F) ​​of the optical glasses of the examples is 0.594 or less, more specifically 0.593 or less, which is within the required range. In particular, the partial dispersion ratio (θg, F) ​​of the optical glasses of the examples (No. B1 to No. B11) is 0.590 or less.

[0234] Here, the partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ) satisfies (-0.00162×ν d +0.630)≦(θg,F)≦(-0.00162×ν d+0.652), in particular, the optical glasses of Examples (No.C1 to No.C12) satisfy (θg, F)≦(-0.00162×ν d +0.650). In addition, the optical glasses of Examples (No.B1 to No.B11) satisfy (θg, F) ​​≤ (-0.00162 × ν d That is, the relationship between the partial dispersion ratio (θg, F) ​​and the Abbe number (ν d ) relationship, such as Figure 2 shown.

[0235] Therefore, it can be clearly seen that the optical glass according to the embodiment of the present invention has a small partial dispersion ratio (θg, F).

[0236] The optical glass of the embodiment of the present invention has a refractive index (n d ) are all above 1.62, more specifically above 1.64, i.e. within the required range. In particular, the optical glasses of Examples (No.C1 to No.C12) have a refractive index (n d ) are all above 1.66.

[0237] In addition, the optical glass of the present invention has a refractive index (n d ) is less than 1.75. In particular, the optical glasses of Examples (No.B1 to No.B11) have a refractive index (n d ) is below 1.68.

[0238] In addition, the optical glass of the embodiment of the present invention has an Abbe number (ν d ) are all above 30, and the Abbe number (ν d ) are all below 42, more specifically below 41, which are all within the required range. In particular, the optical glasses of Examples (No.A1 to No.A27, No.B1 to No.B11) have an Abbe number (ν d ) are all above 34. In addition, the optical glasses of Examples (No.C1 to No.C12) have Abbe numbers (ν d ) are all below 39.

[0239] Here, the optical glass of the embodiment of the present invention has a refractive index (n d ) and the Abbe number (ν d ) satisfies (-0.012ν d +2.04)≦n d ≦(-0.012ν d +2.16), more specifically (-0.012ν d +2.08)≦n d≦(-0.012ν d In particular, the refractive index (n d ) and the Abbe number (ν d ) satisfies (-0.012ν d +2.08)≦n d ≦(-0.012ν d +2.13). In addition, the optical glasses of Examples (No.B1 to No.B11) have a refractive index (n d ) and the Abbe number (ν d ) satisfies (-0.012ν d +2.08)≦n d ≦(-0.012ν d In addition, the optical glasses of Examples (No.C1 to No.C12) have a refractive index (n d ) and the Abbe number (ν d ) satisfies (-0.012ν d +2.09)≦n d ≦(-0.012ν d In addition, the refractive index (n d ) and the Abbe number (ν d ) relationship, such as Figure 3 shown.

[0240] Therefore, it can be clearly seen that the optical glass of the embodiment has a refractive index (n d ) and the Abbe number (ν d ) is within the required range and the partial dispersion ratio (θg, F) ​​is small.

[0241] In addition, the optical glasses of the examples all have λ5 (wavelength at 5% transmittance) below 400nm, more specifically below 350nm. In particular, the optical glasses of the examples (No.B1 to No.B11) all have λ5 (wavelength at 5% transmittance) below 340nm.

[0242] In addition, the optical glass of the embodiment, λ 80 (wavelength at which the transmittance is 80%) is below 450nm, more specifically below 440nm. In particular, the optical glasses of Examples (No.B1 to No.B11) have λ 80 (wavelength when the transmittance is 80%) is less than 390nm. In addition, the optical glasses of Examples (No.C1 to No.C12) have λ 80 (Wavelength when transmittance is 80%) is all below 420nm.

[0243] Therefore, it is also clear that the optical glass of the example has a high transmittance to visible light and little coloration.

[0244] In addition, the specific gravity of the optical glasses of the embodiments is less than 3.80, more specifically less than 3.60, that is, within the required range. In particular, the specific gravity of the optical glasses of the embodiments (No.A1 to No.A27) is less than 3.30 nm. In addition, the specific gravity of the optical glasses of the embodiments (No.B1 to No.B11) is less than 3.00 nm.

[0245] In addition, the optical glasses of the examples have a glass transition temperature of 650°C or less, more specifically, 630°C or less. In particular, the optical glasses of the examples (No.B1 to No.B11) have a glass transition temperature of 600°C or less. In addition, the optical glasses of the examples (No.C1 to No.C12) have a glass transition temperature of 550°C or less.

[0246] In addition, the yield points of the optical glasses of the examples are all below 700°C, that is, within the required range. In particular, the yield points of the optical glasses of the examples (No.B1 to No.B11) are below 670°C. In addition, the yield points of the optical glasses of the examples (No.C1 to No.C12) are below 620°C.

[0247] Based on this, it can be inferred that glass can be press-molded at a lower temperature.

[0248] In addition, the average linear expansion coefficient (α) of the optical glass of the embodiment is 150×10 －7 K －1 More specifically, in 140×10 －7 K －1 In particular, the average linear expansion coefficient (α) of the optical glasses of Examples (No.B1 to No.B11, No.C1 to No.C12) is within 110×10 －7 K －1 the following.

[0249] Furthermore, when a lens preform was formed using the optical glass of the embodiment and the lens preform was press-molded, devitrification and opalescence did not occur and the lens preform could be processed into various lens shapes.

[0250] The present invention has been specifically described above for the purpose of illustration. However, the present embodiment is always for the purpose of illustration only. It should be understood that various changes 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, It is characterized in that Calculated in mass %, Contains SiO 2 The component is more than 20.0% and less than 50.0%, Nb 2 O 5 The component is more than 7.0% and less than 29.59%, and Na 2 The O component is more than 5.0% and less than 20.0%, ZrO 2 The composition is more than 4.0% and less than 13.0% B 2 O 3 The content of ingredients is below 12.27%, R 2 The sum of the mass of the O component is more than 10.0% and less than 30.0%, wherein Rn is one or more selected from the group consisting of Li, Na, and K, The sum of the mass of the RO components is less than 15.0%, wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba, Furthermore, it has a refractive index (n d ), Abbe number (ν 30 or more and less than 42 d ), Partial dispersion ratio (θg, F) ​​below 0.

594.

2. The optical glass according to claim 1, It is characterized in that Mass ratio (Li 2 O+Na 2 O) / (ZrO 2 ) is greater than 0.

50.

3. The optical glass according to claim 1, It is characterized in that Calculated by mass%, Li 2 The content of the O component is 20.0% or less.

4. The optical glass according to claim 1, It is characterized in that Mass ratio (SiO 2 ) / (SiO 2 +B 2 O 3 ) is greater than 0.

50.

5. The optical glass according to claim 1, It is characterized in that Mass ratio (SiO 2 ) / (SiO 2 +B 2 O 3 ) is less than 0.

95.

6. The optical glass according to claim 1, It is characterized in that Calculated in mass %, K 2 O content is 0 to 20.0%, TiO 2 The composition is 0~20.0%, MgO content is 0-10.0%, The CaO content is 0 to 10.0%, The SrO content is 0 to 10.0%, BaO content is 0 to 20.0%, Ta 2 O 5 The composition is 0~10.0%, La 2 O 3 The composition is 0~10.0%, G 2 O 3 The composition is 0~10.0%, Y 2 O 3 The composition is 0~20.0%, Yb 2 O 3 The composition is 0 to 10.0%. P 2 O 5 The composition is 0~10.0%, GeO 2 The composition is 0~10.0%, Al 2 O 3 The composition is 0~15.0%, Ga 2 O 3 The composition is 0~10.0%, WO 3 The composition is 0~10.0%, Bi 2 O 3 The composition is 0~10.0%, The ZnO content is 0 to 30.0%, TeO 2 The composition is 0~15.0%, SnO 2 The composition is 0-5.0%, Sb 2 O 3 The composition is 0-1.0%.

7. The optical glass according to claim 1, It is characterized in that Mass ratio Li 2 O / R 2 O is 0.01 or more.

8. The optical glass according to claim 1, It is characterized in that Ln 2 O 3 The total mass of the components is 20.0% or less, wherein Ln is one or more selected from the group consisting of Y, La, Gd, and Yb.

9. A preform for polishing and / or precision stamping, It is characterized in that The optical glass is composed of any one of claims 1 to 8.

10. An optical element, It is characterized in that The optical glass is composed of any one of claims 1 to 8.

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