Optical glass, preforms and optical components

Abstract

Optical glass, preform and optical element. Optical glass is provided at a lower cost, and the refractive index and Abbe number are within the desired range, which is suitable for optical elements that contribute to the lightness and stability of optical equipment. The optical glass contains 15.0-35.0% of B2O3 component, 20.0%-41.58% of La2O3 component, the content of Nb2O5 component is 3.0% or less, WO3 component is 3.0% or less, Ta2O5 component is 0.1% or less, and ZrO2 component is 6.00% or less. The optical glass has a refractive index of 1.80 or more, an Abbe number of 35-40 and a specific gravity of 4.80 or less, the mass sum of Ln2O3 components is 20.0% or more and 41.58% or less, Ln is one or more selected from La, Gd, Y, and Yb, and (Nb2O5+WO3) / (La2O3+Gd2O3+Ta2O5) is 0.05 or less.

Description

[0001] The present application is a divisional application of an application filed on October 26, 2015, with application number 2015107034126 and invention name “Optical glass, preform and optical element”. Technical Field

[0002] The invention relates to optical glass, preform and optical element. Background Art

[0003] In recent years, the digitization and high-precision of equipment using optical systems have developed rapidly. In the field of various optical equipment such as photographic equipment such as digital cameras and camcorders, image playback (projection) equipment such as projectors and projection televisions, there is an increasing demand to reduce the number of optical elements such as lenses and prisms used in the optical system and to make the overall optical system lighter and smaller.

[0004] Optical glass used to make optical elements, especially glass with a refractive index of 1.75 or more, which can achieve lightweight and miniaturization of the entire optical system, is highly valued. d ), having an Abbe number (ν 30 or more and 40 or less d ) is in great demand. As such high refractive index low dispersion glass, glass compositions represented by Patent Documents 1 to 3 are known.

[0005] Prior art literature

[0006] Patent Literature

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 52-103412

[0008] [Patent Document 2] Japanese Patent Application Publication No. 2008-120677

[0009] [Patent Document 3] Japanese Patent Application Publication No. 2014-047099 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In order to reduce the material cost of optical glass, it is desired that the raw materials of optical glass be as cheap as possible. However, although the glass compositions described in Patent Documents 1 to 3 contain Ta, an expensive raw material component, as little as possible, 2 O 5 components, but on the other hand, contains a large amount of Nb 2 O 5 Ingredients,WO 3 and Gd 2 O 3 Ingredients, Yb 2 O 3Rare earth components such as components still contain expensive raw materials, so it is difficult to say that the above requirements are fully met.

[0012] In addition, it is also possible to replace these expensive components with a larger amount of TiO 2 However, glass containing a large amount of such inexpensive high refractive index components is often colored and is not suitable for use in optical elements such as lenses and prisms that transmit visible light.

[0013] The present invention has been made in view of the above-mentioned problems, and its object is to obtain an optical glass at a lower cost, wherein the optical glass has not only a refractive index (n d ) and Abbe number (ν d ) is within the desired range and is suitable for stable optical elements that can contribute to the lightweighting of optical equipment.

[0014] Means for solving problems

[0015] The inventors of the present invention have repeatedly conducted intensive experiments and studies to solve the above problems. As a result, they have found that 2 O 3 Ingredients and La 2 O 3 In the glass with Nb 2 O 5 The component is less than 5.0%, and WO 3 The content is less than 5.0%, that is, the expensive raw material Nb is not contained as much as possible. 2 O 5 Ingredients,WO 3 The present invention has been completed by achieving a glass having a low specific gravity while maintaining a desired refractive index and Abbe number. Specifically, the present invention provides the following solutions.

[0016] (1) An optical glass characterized by containing 15.0 to 35.0% by mass of B 2 O 3 Composition, 20.0% to 60.0% La 2 O 3 Composition, Nb 2 O 5 The content of the component is less than 5.0%, WO 3 The content of the component is 5.0% or less, and the optical glass has a refractive index (n d ), and a specific gravity of less than 4.80.

[0017] (2) The optical glass as described in (1), characterized in that, by weight and (La 2 O3 +Gd 2 O 3 +Ta 2 O 5 ) is 25.0~60.0%.

[0018] (3) The optical glass according to (1) or (2), wherein, by mass ratio, (Nb 2 O 5 +WO 3 ) / (La 2 O 3 +Gd 2 O 3 +Ta 2 O 5 ) is less than 0.25.

[0019] (4) The optical glass according to any one of (1) to (3), wherein the mass ratio of ZnO / BaO is greater than 0 and is 5.0 or less.

[0020] (5) The optical glass according to any one of (1) to (4), characterized in that, by weight, (Nb 2 O 5 +WO 3 +TiO 2 ) is greater than 0 and less than 20.0%.

[0021] (6) The optical glass according to any one of (1) to (5), wherein, in terms of mass %,

[0022] G 2 O 3 The composition is 0~20.0%,

[0023] Y 2 O 3 The composition is 0~20.0%,

[0024] Yb 2 O 3 The composition is 0~10.0%,

[0025] Lu 2 O 3 The composition is 0-5.0%,

[0026] Ta 2 O 5 The composition is 0-5.0%.

[0027] (7) The optical glass according to any one of (1) to (6), wherein Ln 2 O 3The mass sum of the components (wherein Ln is one or more selected from La, Gd, Y, and Yb) is 15.0% to 60.0%.

[0028] (8) The optical glass according to any one of (1) to (7), wherein, in terms of mass %,

[0029] SiO 2 The composition is 0~15.0%,

[0030] TiO 2 The composition is 0~20.0%,

[0031] ZrO 2 The composition is 0 to 10.0%.

[0032] (9) The optical glass according to any one of (1) to (8), wherein, in terms of mass %,

[0033] The CaO content is 0 to 15.0%,

[0034] BaO content is 0 to 15.0%,

[0035] MgO content is 0-10.0%,

[0036] The SrO content is 0 to 10.0%,

[0037] The ZnO content is 0 to 25.0%.

[0038] (10) The optical glass according to any one of (1) to (9), wherein the mass sum of RO components (wherein R is one or more selected from Mg, Ca, Sr, and Ba) is 30.0% or less.

[0039] (11) The optical glass according to any one of (1) to (10), wherein, in terms of mass %,

[0040] Li 2 O content is 0 to 5.0%,

[0041] Na 2 O content is 0 to 5.0%,

[0042] K 2 The O component is 0 to 5.0%.

[0043] (12) The optical glass according to any one of (1) to (11), wherein Rn 2 The mass sum of O components (wherein Rn is one or more selected from Li, Na, and K) is 5.0% or less.

[0044] (13) The optical glass according to any one of (1) to (12), wherein, in terms of mass %,

[0045] P 2 O 5 The composition is 0~10.0%,

[0046] GeO 2 The composition is 0~10.0%,

[0047] Bi 2 O 3 The composition is 0~10.0%,

[0048] TeO 2 The composition is 0-5.0%,

[0049] Al 2 O 3 The composition is 0-5.0%,

[0050] Ga 2 O 3 The composition is 0-5.0%,

[0051] SnO content is 0-3.0%,

[0052] Sb 2 O 3 The composition is 0-3.0%.

[0053] (14) The optical glass according to any one of (1) to (13), which has an Abbe number (νd) of 30 to 45.

[0054] (15) The optical glass according to any one of (1) to (14), wherein the spectral transmittance shows a wavelength (λ 70 ) is below 450nm.

[0055] (16) A preform for polishing and / or precision press molding, which is formed of the optical glass according to any one of (1) to (15).

[0056] (17) An optical element formed by grinding and / or polishing the optical glass according to any one of (1) to (15).

[0057] (18) An optical element formed by precision press molding the preform described in (16).

[0058] Effects of the Invention

[0059] According to the present invention, an optical glass having not only a refractive index (n d ) and Abbe number (ν d) is within the desired range and is suitable for stable optical elements that can contribute to the lightweighting of optical equipment. DETAILED DESCRIPTION

[0060] The optical glass of the present invention contains 15.0 to 35.0% of B in terms of mass % relative to the total mass of the glass in terms of oxide composition. 2 O 3 Composition, 20.0~60.0% La 2 O 3 Composition, Nb 2 O 5 The content of the component is less than 5.0%, WO 3 The content of the component is 5.0% or less, and has a refractive index (n d ), and a specific gravity of less than 4.5. 2 O 3 Ingredients and La 2 O 3 In the glass with the same composition, even if the expensive raw material Nb is not contained as much as possible, 2 O 5 Ingredients,WO 3 Components having a refractive index (n) of 1.75 or more can also be obtained. d ), and an optical glass with a specific gravity of 4.5 or less, and in addition, a cheaper optical glass can be provided.

[0061] Hereinafter, the embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments and can be implemented by appropriate changes within the scope of the purpose of the present invention. It should be noted that the description is repeated and sometimes the description is appropriately omitted, but it does not limit the gist of the invention.

[0062] [Glass composition]

[0063] The composition range of each component constituting the optical glass of the present invention is as follows. In this specification, unless otherwise specified, the content of each component is expressed in mass % relative to the total mass of the glass converted to the composition of oxides. Here, "composition converted to oxides" refers to the following composition: assuming that the oxides, complex salts, metal fluorides, etc. used as raw materials for the glass components of the present invention are all decomposed and converted into oxides when melted, at this time, the total mass of the generated oxides is taken as 100 mass % to express the components contained in the glass.

[0064] <Required ingredients, optional ingredients>

[0065] B 2 O 3 The components are glass-forming components and are essential components for the optical glass of the present invention.

[0066] In particular, by containing 15.0% or more of B 2 O 3 The composition can not only reduce the specific gravity, but also promote the formation of stable glass, reduce devitrification, and improve the thermal stability of glass. 2 O 3 The lower limit of the content of the component is preferably 15.0%, more preferably 17.0%, further preferably 20.0%.

[0067] On the other hand, by making B 2 O 3 The content of the component is 35.0% or less, which can suppress the decrease in the refractive index of the glass and the deterioration of chemical durability. 2 O 3 The upper limit of the content of the component is preferably 35.0%, more preferably 33.0%, further preferably 28.0%.

[0068] About B 2 O 3 As raw material, H 3 BO 3 、Na 2 B 4 O 7 、Na 2 B 4 O 7 10H 2 O. BPO 4 wait.

[0069] La 2 O 3 La is a component that can increase the refractive index and Abbe number of glass when contained in an amount of 20.0% or more. It is also a relatively cheap component among rare earth elements and effectively suppresses the increase in glass material costs. 2 O 3 The components are components that should be contained in the optical glass of the present invention. 2 O 3 The lower limit of the content of the component is preferably 20.0%, more preferably 25.0%, further preferably 30.0%, and further preferably 33.0%.

[0070] On the other hand, by making La 2 O 3 The content of the component is 60.0% or less, which can reduce the devitrification of the glass. 2 O 3 The upper limit of the content of the component is preferably 60.0%, more preferably 50.0%, further preferably 45.0%.

[0071] About La 2 O 3 Ingredients, La can be used as raw materials 2 O 3 、La(NO 3 ) 3 ·XH 2 O (X is an arbitrary integer), etc.

[0072] By making Nb 2 O 5 The content of the component is less than 5.0%, which can reduce the expensive Nb 2 O 5 The use of NbO2 components can reduce the material cost of glass. In addition, since the rise in the dissolve temperature during glass manufacturing can be suppressed, the manufacturing cost of glass can also be reduced. In addition, the 2 O 5 The visible light transmittance of the glass is reduced due to the Nb component. 2 O 5 The upper limit of the content of the component is preferably 5.0%, more preferably 4.0%, further preferably 3.0%, and most preferably not contained.

[0073] About Nb 2 O 5 As raw material, Nb can be used 2 O 5 wait.

[0074] By making WO 3 The content of the component is less than 5.0%, which can reduce the expensive WO 3 The use of components can reduce the material cost of glass. In addition, it can reduce the 3 The coloring of glass caused by the composition increases the visible light transmittance and reduces the specific gravity. 3 The upper limit of the content of the component is preferably 5.0%, more preferably 4.0%, further preferably 3.0%, and most preferably not contained.

[0075] About WO 3 Ingredients, WO can be used 3 etc. are contained in the glass as raw materials.

[0076] The La in the optical glass of the present invention 2 O 3 Ingredients, Gd 2 O 3 Ingredients and 2 O 5 The total amount of the components is preferably 25.0% or more and 60.0% or less. 2O 3 +Gd 2 O 3 +Ta 2 O 5 ) is 25.0% or more, a glass having a desired refractive index and Abbe number can be obtained, and glass can be obtained stably. Therefore, the lower limit of the mass sum is preferably 25.0%, and the lower limit is more preferably 30.0%, and further preferably 35.0%.

[0077] On the other hand, by making the mass and (La 2 O 3 +Gd 2 O 3 +Ta 2 O 5 ) is less than 60.0%, which can reduce material costs. Therefore, quality and (La 2 O 3 +Gd 2 O 3 +Ta 2 O 5 ) is preferably 60.0%, more preferably 55.0%, further preferably 50.0%, and most preferably 45.0%.

[0078] The Nb in the optical glass of the present invention 2 O 5 Ingredients and WO 3 The content of ingredients relative to La 2 O 3 Ingredients, Gd 2 O 3 Ingredients and Ta 2 O 5 The ratio (mass ratio) of the content of the components is preferably 0.25 or less. In this way, not only can a glass having a desired refractive index and Abbe number be obtained, but also the specific gravity can be reduced, and the Nb content can be reduced. 2 O 5 , WO 3 Therefore, the mass ratio (Nb 2 O 5 +WO 3 ) / (La 2 O 3 +Gd 2 O 3 +Ta 2 O 5 ) is preferably 0.25 or less, more preferably 0.15 or less, further preferably 0.10 or less, and most preferably 0.05 or less.

[0079] The ratio (mass ratio) of the content of the ZnO component in the optical glass of the present invention to the BaO component is preferably greater than 0 and less than 5.0. By making the mass ratio of (ZnO) / (BaO) greater than 0, the stability of the glass during molding can be improved. Therefore, the mass ratio can be preferably greater than 0, and its lower limit is more preferably 0.1, and further preferably greater than 0.5.

[0080] On the other hand, by setting the mass ratio of (ZnO) / (BaO) to 5.0 or less, the specific gravity of the glass can be reduced. Therefore, the upper limit of the mass ratio is preferably 5.0, more preferably 4.9, and further preferably 4.8.

[0081] The Nb in the optical glass of the present invention 2 O 5 Ingredients,WO 3 Composition and TiO 2 When the total amount of the components is greater than 0%, it is possible to adjust to a high refractive index and high dispersion, so it is easy to obtain the desired optical constants. 2 O 5 +WO 3 +TiO 2 ) may preferably be greater than 0%, and its lower limit is more preferably 3.0%, and further preferably 6.0%.

[0082] On the other hand, by making the mass and (Nb 2 O 5 +WO 3 +TiO 2 ) is less than 20.0%, which can reduce the coloring of the glass and improve the visible light transmittance of the glass. 2 O 5 +WO 3 +TiO 2 ) is preferably 20.0%, more preferably 15.0%, and further preferably 12.5%.

[0083] G 2 O 3 Ingredients, Y 2 O 3 Ingredients, Yb 2 O 3 Lu 2 O 3 The component is an optional component that can increase the refractive index and Abbe number of the glass and reduce devitrification when contained in an amount greater than 0%.

[0084] On the other hand, by making Gd 2 O 3 Ingredients, Y 2 O 3 The contents of the components are 20.0% or less, and Yb2 O 3 The content of the component is less than 10.0%, and Lu 2 O 3 The content of Gd is 5.0% or less, which can reduce the use of these expensive components, thereby reducing the material cost of glass. In addition, it can suppress the unnecessary increase of the Abbe number of glass and devitrification caused by excessive inclusion of these components. 2 O 3 Ingredients, Y 2 O 3 The upper limit of the content of the component is preferably 20.0%, more preferably 15.0%, further preferably 10.0%, further preferably less than 5.0%, and further preferably less than 3.0%. 2 O 3 The upper limit of the content of the component is preferably 10.0%, more preferably less than 5.0%, and further preferably less than 3.0%. 2 O 3 The upper limit of the content of the component is preferably 5.0%, more preferably less than 3.0%, and further preferably less than 1.0%.

[0085] About Gd 2 O 3 Ingredients, Y 2 O 3 Ingredients, Yb 2 O 3 Lu 2 O 3 Ingredients, Gd can be used 2 O 3 , GdF 3 , Y 2 O 3 , YF 3 , Yb 2 O 3 、Lu 2 O 3 etc. are contained in the glass as raw materials.

[0086] Ta 2 O 5 The component is an optional component which can increase the refractive index of glass and reduce devitrification when contained in an amount greater than 0%.

[0087] On the other hand, by making Ta 2 O 5 The content of the component is less than 5.0%, which can reduce the expensive Ta 2 O 5 The use of components can reduce the material cost of glass. In addition, by reducing Ta 2 O5 The use of Ta components can reduce the melting temperature of raw materials, which can reduce the energy required for raw material dissolution, thereby reducing the manufacturing cost of optical glass. 2 O 5 The upper limit of the content of the component is preferably 5.0%, more preferably 3.0%, further preferably 1.0%, further preferably 0.1%, and most preferably no content.

[0088] About Ta 2 O 5 Ingredients, Ta can be used 2 O 5 etc. are contained in the glass as raw materials.

[0089] The Ln in the optical glass of the present invention 2 O 3 The total amount of the components (wherein Ln is one or more selected from La, Gd, Y, and Yb) is preferably 15.0% to 60.0%.

[0090] In particular, by making the total amount 15.0% or more, the Abbe number of the glass can be increased. 2 O 3 The lower limit of the total amount (mass sum) of the components is preferably 15.0%, more preferably 20.0%, further preferably 25.0%, and most preferably 30.0%.

[0091] On the other hand, by making the total amount less than 60.0%, not only can the devitrification of the glass be reduced, but also the use of expensive rare earths can be reduced, thereby reducing the material cost of the glass. 2 O 3 The upper limit of the mass sum of the components is preferably 60.0%, more preferably 50.0%, further preferably 45.0%.

[0092] SiO 2 The component is an optional component that can reduce the specific gravity, increase the viscosity of the glass, and reduce the devitrification of the glass when contained in an amount greater than 0%. 2 The content of the component may be preferably greater than 1.0%, more preferably greater than 2.0%, and further preferably greater than 4.0%.

[0093] On the other hand, by making SiO 2 The content of the component is 15.0% or less, which can suppress the increase of the glass transition temperature and the decrease of the refractive index. 2 The upper limit of the content of the component is preferably 15.0%, more preferably 10.0%, further preferably 8.0%.

[0094] About SiO 2Ingredients, SiO 2 , K 2 SiF 6 、Na 2 SiF 6 etc. are contained in the glass as raw materials.

[0095] TiO 2 TiO is an optional component that can increase the refractive index of the glass and adjust the Abbe number to a low level when contained in an amount greater than 0%. 2 The content of the component may preferably be greater than 0%, and the lower limit thereof is more preferably 1.0%, further preferably 3.0%, and further preferably 5.0%.

[0096] On the other hand, by making TiO 2 The content of the component is less than 20.0%, which can inhibit the 2 The devitrification of the glass caused by the components becoming crystal nuclei can be suppressed from decreasing the Abbe number more than necessary, and the amount of glass produced by the inclusion of TiO can be reduced. 2 The coloring of glass caused by the TiO component can increase the visible light transmittance. 2 The upper limit of the content of the component is preferably 20.0%, more preferably 15.0%, further preferably 12.0%.

[0097] About TiO 2 Ingredients, TiO 2 etc. are contained in the glass as raw materials.

[0098] ZrO 2 The component is an optional component that contributes to the high refractive index and low dispersion of the glass and can reduce the devitrification of the glass when contained in an amount greater than 0%. 2 The content of the component may be preferably greater than 0%, more preferably greater than 0.5%, further preferably greater than 1.0%, and most preferably greater than 3.0%.

[0099] On the other hand, by making ZrO 2 The content of the component is 10.0% or less, which can suppress the increase in the melting temperature during glass production, thereby suppressing the increase in the production cost of glass. 2 The upper limit of the content of the component is preferably 10.0%, more preferably 9.0%, further preferably 8.0%.

[0100] About ZrO 2 As raw material, ZrO can be used 2 , ZrF 4 wait.

[0101] When CaO, BaO, MgO and SrO are contained in an amount exceeding 0%, they are optional components which can adjust the refractive index of glass, improve the solubility of glass raw materials and reduce devitrification.

[0102] On the other hand, by making the contents of the CaO component and the BaO component less than 15.0% respectively, and making the contents of the MgO component and the SrO component less than 10.0% respectively, it is possible to suppress the unnecessary reduction of the refractive index of the glass and devitrification. The upper limit of the contents of the CaO component and the BaO component is preferably 15.0%, more preferably 10.0%, and further preferably 8.0%. In addition, the upper limit of the contents of the MgO component and the SrO component is preferably 10.0%, more preferably 5.0%, and further preferably 3.0%. In particular, since at least one of the BaO component and the SrO component can reduce the specific gravity, it is preferably contained in an amount greater than 0%, more preferably 1%, and further preferably 2% as the lower limit.

[0103] As for the MgO component, the CaO component, the SrO component, and the BaO component, MgCO 3 MgF 2 、CaCO 3 , CaF 2 、Sr(NO 3 ) 2 , SrF 2 、BaCO 3 ,Ba(NO 3 ) 2 , BaF 2 wait.

[0104] The ZnO component is an optional component that can adjust the refractive index of the glass, improve the solubility of the glass raw materials, and reduce devitrification when contained in an amount greater than 0% within the range of the refractive index and Abbe number of the present invention. Therefore, the content of the ZnO component can be preferably greater than 0%, more preferably greater than 3.0%, and further preferably greater than 5.0%.

[0105] On the other hand, by making the content of the ZnO component 25.0% or less, not only the increase in specific gravity can be suppressed, but also devitrification caused by excessive ZnO content can be suppressed. In addition, by suppressing the decrease in viscosity of the molten glass, the generation of ribs in the glass can be reduced. Therefore, the upper limit of the content of the ZnO component is preferably 25.0%, more preferably 20.0%, and further preferably 15.0%.

[0106] Regarding the ZnO component, ZnO, ZnF 2 wait.

[0107] In the optical glass of the present invention, the total amount of RO components (wherein R is one or more selected from Mg, Ca, Sr, and Ba) is preferably 30.0% or less. This can suppress the decrease in the refractive index of the glass and the increase in the liquidus temperature caused by excessive inclusion of RO components, and can reduce the specific gravity. Therefore, the upper limit of the total amount (mass sum) of RO components is preferably 25.0%, more preferably 20.0%, and further preferably 15.0%.

[0108] On the other hand, from the viewpoint of improving the solubility of glass raw materials and reducing devitrification, the mass sum of the RO component may be preferably greater than 0%, more preferably 1.0% or more, and even more preferably 3.0% or more.

[0109] Li 2 The O component is an optional component which, when contained in an amount exceeding 0%, can improve the solubility of glass raw materials, reduce devitrification when the glass is reheated, and reduce the specific gravity.

[0110] On the other hand, by making Li 2 The content of O component is 5.0% or less, so that it is difficult to reduce the refractive index of the glass, and it is possible to reduce the 2 O component causes devitrification of glass. In particular, Li 2 The refractive index of glass containing O is likely to be low and the Abbe number is likely to be high. 2 The upper limit of the content of the O component is preferably 5.0%, more preferably 3.0%, further preferably 1.0%, further preferably less than 0.5%, further preferably less than 0.35%, further preferably less than 0.3%.

[0111] About Li 2 O component, Li can be used as a raw material 2 CO 3 、LiNO 3 , LiF, etc.

[0112] Na 2 O component, K 2 O component and Cs 2 The O component is an optional component which can improve the solubility of glass raw materials when contained in an amount exceeding 0%, reduce devitrification when the glass is reheated, and reduce the specific gravity.

[0113] On the other hand, by making the contents of these components less than 5.0%, it is difficult to reduce the refractive index of the glass, and it is possible to reduce the devitrification caused by excessive inclusion of these components. 2 O component, K 2 O component and Cs 2The upper limit of each content of the O component is preferably 5.0%, more preferably 3.0%, further preferably 1.0%.

[0114] About Na 2 O component, K 2 O component and Cs 2 O component, NaNO can be used as raw material 3 , NaF, Na 2 SiF 6 , K 2 CO 3 、KNO 3 , KF, KHF 2 , K 2 SiF 6 , Cs 2 CO 3 , CsNO 3 wait.

[0115] In the optical glass of the present invention, Rn 2 The total amount of the O component (wherein Rn is one or more selected from Li, Na, K and Cs) is preferably 5.0% or less. This makes it difficult to lower the refractive index of the glass, and can reduce the risk of excessive Rn 2 O component causes devitrification. Therefore, Rn 2 The upper limit of the total amount (mass sum) of the O component is preferably 5.0%, more preferably 3.0%, and further preferably less than 1.0%.

[0116] P 2 O 5 The component is an optional component that can lower the liquidus temperature of glass and reduce devitrification when contained in an amount greater than 0%.

[0117] On the other hand, by making P 2 O 5 The content of the component is 10.0% or less, which can suppress the reduction of the chemical durability of the glass, especially the water resistance. 2 O 5 The upper limit of the content of the component is preferably 10.0%, more preferably 5.0%, further preferably 3.0%.

[0118] About P 2 O 5 As raw materials, Al(PO 3 ) 3 、Ca(PO 3 ) 2 、Ba(PO 3 ) 2 , BPO 4 , H 3 PO 4wait.

[0119] GeO 2 The component is an optional component that can increase the refractive index of the glass and lower the liquidus temperature of the glass when contained in an amount greater than 0%.

[0120] On the other hand, by reducing the expensive GeO 2 The composition can enhance the effect of reducing the material cost of the glass of the present invention. 2 The content of the component is preferably 10.0% or less, and the upper limit thereof is more preferably 5.0%, and further preferably 1.0%.

[0121] About GeO 2 As raw material, GeO can be used 2 wait.

[0122] Bi 2 O 3 The component is an optional component that can increase the refractive index and lower the glass transition temperature when contained in an amount greater than 0%.

[0123] On the other hand, by making Bi 2 O 3 The content of the component is 10.0% or less, which can improve the visible light transmittance of the glass by reducing the devitrification of the glass and reducing the coloring of the glass. 2 O 3 The upper limit of the content of the component is preferably 10.0%, more preferably 5.0%, further preferably 3.0%.

[0124] About Bi 2 O 3 As raw material, Bi can be used 2 O 3 wait.

[0125] TeO 2 The component is an optional component that can increase the refractive index of glass and lower the glass transition temperature when contained in an amount greater than 0%.

[0126] On the other hand, by making TeO 2 The content of the component is less than 5.0%, which can reduce TeO 2 The alloying of components with dissolving equipment (especially precious metals such as Pt) can extend the life of the dissolving equipment. In addition, by reducing the expensive TeO 2 composition, which can reduce the material cost of glass. 2 The upper limit of the content of the component is preferably 5.0%, more preferably less than 3.0%, and further preferably less than 1.0%.

[0127] About TeO2 As raw material, TeO 2 wait.

[0128] Al 2 O 3 Composition and Ga 2 O 3 The component is an optional component that can improve the chemical durability of glass and reduce the devitrification when the glass raw material is dissolved when it is contained in an amount greater than 0%. In particular, when Al is contained in an amount greater than 0%, 2 O 3 When Al is used as a component, the stability of glass during molding can be improved. 2 O 3 The content of the component may preferably be greater than 0%, with a lower limit thereof more preferably being 0.5%, and further preferably greater than 1.0%.

[0129] On the other hand, by making Al 2 O 3 Composition and Ga 2 O 3 The contents of the components are 5.0% or less, respectively, which can reduce the devitrification of the glass caused by excessive inclusion of these components. In addition, by reducing the expensive Ga 2 O 3 composition, which can reduce the material cost of glass. 2 O 3 Composition and Ga 2 O 3 The upper limit of the content of each component is preferably 5.0%, more preferably less than 3.0%, and further preferably less than 2.0%.

[0130] About Al 2 O 3 Composition and Ga 2 O 3 As raw material, Al can be used 2 O 3 、Al(OH) 3 , AlF 3 , Ga 2 O 3 、Ga(OH) 3 wait.

[0131] SnO 2 The component is an optional component that can clarify molten glass and improve the visible light transmittance of glass when contained in an amount greater than 0%.

[0132] On the other hand, by making SnO 2The content of the component is 3.0% or less, which can make the coloring of the glass and the devitrification of the glass due to the reduction of the molten glass less likely to occur. In addition, since SnO 2 The alloying of SnO with dissolving equipment (especially precious metals such as Pt) can prolong the life of the dissolving equipment. 2 The upper limit of the content of the component is preferably 3.0%, more preferably 1.0%, and further preferably 0.5%.

[0133] About SnO 2 As raw materials, SnO, SnO 2 、SnF 2 、SnF 4 wait.

[0134] Sb 2 O 3 The component is an optional component that can improve the visible light transmittance of the glass when contained in an amount greater than 0%, and can also perform degassing when the glass raw materials are dissolved.

[0135] On the other hand, by making Sb 2 O 3 The content of the component is 3.0% or less, which can suppress excessive foaming when the glass raw material is dissolved. 2 O 3 The alloying of components with dissolving equipment (especially precious metals such as Pt) becomes difficult, which can extend the life of dissolving equipment. 2 O 3 If the content of Sb is too high, the visible light transmittance of the glass will decrease. 2 O 3 The upper limit of the content of the component is preferably 3.0%, more preferably 2.0%, further preferably less than 1.0%, and most preferably less than 0.5%.

[0136] About Sb 2 O 3 As raw material, Sb can be used 2 O 3 , Sb 2 O 5 、Na 2 H 2 Sb 2 O 7 ·5H 2 O etc.

[0137] It should be noted that the component for clarifying the glass and performing degassing is not limited to the above-mentioned Sb. 2 O 3 As the component, a clarifier, a degassing agent or a combination thereof known in the glass manufacturing field can be used.

[0138] <About ingredients that should not be contained>

[0139] Next, components that should not be contained in the optical glass of the present invention and components that are undesirable when contained will be described.

[0140] Other components may be added as needed within a range that does not impair the properties of the glass of the present invention. However, each transition metal component such as Ce, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo has the property of causing coloration of the glass even when contained in a small amount alone or in combination, or causing absorption at a specific wavelength in the visible region, thereby canceling the effect of improving the visible light transmittance of the present invention. Therefore, in optical glass that transmits wavelengths in the visible region, it is preferred that the above components are substantially not contained.

[0141] In addition, lead compounds such as PbO, and each component of Th, Cd, Tl, Os, Be, Se have a tendency to control their use as harmful chemical substances in recent years, not only in the manufacturing process of glass, but also until the processing process and the processing after productization, the measures of environmental countermeasures are needed. Therefore, when paying attention to the impact of environmental aspects, except for the inevitable mixing, it is preferred that the above-mentioned components are not substantially contained. Thus, the optical glass does not substantially contain environmentally polluting substances. Therefore, even if the measures of special environmental countermeasures are not taken, the optical glass can also be manufactured, processed, and discarded.

[0142] The content range of each component in the present invention is expressed as mass % relative to the total mass of the glass in terms of the composition converted into oxides, and therefore is not directly expressed as mol %. However, the composition expressed as mol % of each component present in the glass composition satisfying the various physical properties required in the present invention generally takes the following values ​​in terms of the composition converted into oxides.

[0143] B 2 O 3 The composition is 5.0 to 70.0 mol%.

[0144] La 2 O 3 The component is 3.0 to 40.0 mol%, and

[0145] Nb 2 O 5 The composition is 0 to 20.0 mol%.

[0146] WO 3 The composition is 0 to 25.0 mol%.

[0147] as well as,

[0148] G2 O 3 The composition is 0 to 10.0 mol%.

[0149] Y 2 O 3 The composition is 0 to 10.0 mol%.

[0150] Yb 2 O 3 The composition is 0 to 10.0 mol%.

[0151] Lu 2 O 3 The composition is 0 to 5.0 mol%.

[0152] Ta 2 O 5 The composition is 0 to 10.0 mol%.

[0153] SiO 2 The composition is 0 to 30.0 mol%.

[0154] TiO 2 The composition is 0 to 40.0 mol%.

[0155] ZrO 2 The composition is 0 to 30.0 mol%.

[0156] The CaO content is 0 to 40.0 mol%.

[0157] BaO content: 0 to 35.0 mol %

[0158] MgO content is 0 to 20.0 mol%.

[0159] SrO content: 0 to 20.0 mol %

[0160] The ZnO content is 0 to 60.0 mol%.

[0161] Li 2 O component is 0 to 30.0 mol%.

[0162] Na 2 O component is 0 to 25.0 mol%.

[0163] K 2 O component is 0 to 20.0 mol%.

[0164] Cs 2 O component is 0 to 10.0 mol%.

[0165] P 2 O 5 The composition is 0 to 15.0 mol%.

[0166] GeO2 The composition is 0 to 10.0 mol%.

[0167] Bi 2 O 3 The composition is 0 to 5.0 mol%.

[0168] TeO 2 The composition is 0 to 25.0 mol%.

[0169] Al 2 O 3 The composition is 0 to 15.0 mol%.

[0170] Ga 2 O 3 The composition is 0 to 5.0 mol%.

[0171] SnO 2 The composition is 0 to 0.3 mol%, or

[0172] Sb 2 O 3 The composition is 0 to 1.0 mol%.

[0173] [Manufacturing method]

[0174] The optical glass of the present invention can be manufactured, for example, in the following manner. That is, the above raw materials are uniformly mixed so that the contents of each component are within a specified range, the prepared mixture is put into a platinum crucible, and the mixture is dissolved in an electric furnace at a temperature range of 1200 to 1400° C. for 3 to 4 hours depending on the solubility of the glass composition, and after being uniformly stirred, the mixture is lowered to an appropriate temperature, and then injected into a mold and slowly cooled to thereby manufacture the glass.

[0175] [physical properties]

[0176] 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 (n d The lower limit of the refractive index is preferably 1.75, more preferably 1.78, and further preferably 1.80. The upper limit of the refractive index is preferably 1.95, more preferably 1.90, and further preferably 1.88. In addition, the Abbe number (ν d ) has a lower limit of preferably 30, more preferably 33, further preferably 35, and an upper limit of preferably 45, more preferably 43, further preferably 40, and most preferably 39.5.

[0177] By having such a high refractive index, a large amount of light refraction can be obtained even if the optical element is thinned. In addition, by having such a low dispersion, even if it is a single lens, the focus shift (chromatic aberration) caused by the difference in light wavelength is small. In addition, by having such a low dispersion, when combined with an optical element with high dispersion (low Abbe number), high imaging characteristics can be achieved.

[0178] Therefore, the optical glass of the present invention is useful in optical design, and in particular, can achieve miniaturization of the optical system while achieving high imaging characteristics, thereby expanding the degree of freedom in optical design.

[0179] In addition, the optical glass of the present invention preferably has a small specific gravity. More specifically, the specific gravity of the optical glass of the present invention is 4.80 or less. As a result, the mass of the optical element and the optical device using the optical element can be reduced, thus contributing to the lightweighting of the optical device. Therefore, the upper limit of the specific gravity of the optical glass of the present invention is preferably 4.80, more preferably 4.60, and further preferably 4.30. It should be noted that the specific gravity of the optical glass of the present invention is generally approximately 3.00 or more, more specifically, 3.50 or more, and further specifically, 4.00 or more.

[0180] 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".

[0181] The optical glass of the present invention preferably has a high visible light transmittance, especially a transmittance of light on the short wavelength side of visible light, so as to have less coloration. In particular, when a sample with a thickness of 10 mm in the optical glass of the present invention is measured, the shortest wavelength (λ 5 The upper limit of ) may be preferably 400 nm, more preferably 380 nm, and further preferably 360 nm. In addition, when a sample with a thickness of 10 mm in the optical glass of the present invention is measured, the shortest wavelength (λ) at which the spectral transmittance is 70% is 70 The upper limit of ) may be preferably 450 nm, more preferably 430 nm, and further preferably 400 nm. In addition, when a sample with a thickness of 10 mm in the optical glass of the present invention is measured, the shortest wavelength (λ) at which the spectral transmittance is 80% 80 ) can be preferably 500nm, more preferably 490nm, and further preferably 480nm. Thus, the absorption end of the glass falls outside the visible region, which can improve the transparency of the glass relative to the light of the wavelength in a wider visible region, and thus, the optical glass can be suitably used for optical elements such as lenses that transmit visible light.

[0182] [Preform and optical element]

[0183] A glass molded body can be made from the produced optical glass using a molding method such as reheating and pressing molding, precision pressing molding, etc. That is, the glass molded body can be made using the following methods: a method of grinding and polishing a gob or glass block formed of optical glass to obtain the shape of an optical element; a method of grinding and polishing a gob or glass block formed of optical glass to obtain a glass molded body by reheating and molding (reheating and pressing molding); and a method of molding (precision pressing molding) a preformed body material obtained by cutting a gob or glass block and grinding it, or a preformed body material molded by known float molding, etc., using an ultra-precision mold to obtain the shape of an optical element. It should be noted that the method of making a glass molded body is not limited to these methods.

[0184] The glass molded body produced as described above is useful for various optical elements and optical designs. It is particularly preferred to use precision press molding or other methods to produce optical elements such as lenses, prisms, and reflectors from the optical glass of the present invention. Thus, when used in optical devices such as cameras and projectors that allow visible light to pass through optical elements, it is possible to achieve high-definition and high-precision imaging characteristics while miniaturizing the optical system in these optical devices.

[0185] Example

[0186] The compositions of the examples (No. 1 to No. 8) and the comparative example (No. A) of the present invention, and the refractive index (n d ), Abbe number (ν d ), specific gravity, and wavelengths (λ 5 , 70 , 80 ) are shown in Table 1 and Table 2. It should be noted that the following examples are for illustrative purposes only and are not limited to these examples.

[0187] The glasses of these embodiments and comparative examples are all made in the following manner: high-purity raw materials used in common optical glasses, such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds, which are equivalent to the raw materials of each component are selected, weighed and evenly mixed in the proportions of the compositions of the embodiments and comparative examples shown in Tables 1 and 2, and then put into a platinum crucible. Depending on the solubility difficulty of the glass composition, they are dissolved in an electric furnace at a temperature range of 1100 to 1500°C for 2 to 5 hours, and then stirred evenly and defoamed, etc., and then injected into a mold and slowly cooled to make glass.

[0188] Here, the refractive index and Abbe number of the glass of the examples and comparative examples were measured based on the Japan Optical Glass Industry Association Standard JOGIS01-2003. It should be noted that the glass used in this measurement was treated in a slow cooling furnace under annealing conditions with a slow cooling rate of -25°C / hr.

[0189] In addition, the specific gravity of the glass of an Example and a comparative example was measured according to JOGIS05-1975 "Measurement method of specific gravity of optical glass".

[0190] In addition, the visible light transmittance of the glass of the embodiment and the comparative example was measured according to the Japanese Optical Glass Industry Association standard JOGIS02. It should be noted that in the present invention, the glass transmittance is measured to determine whether the glass is colored and the degree of coloration. Specifically, according to JIS Z8722, the spectral transmittance of 200 to 800 nm of the parallel polished product with a thickness of 10 ± 0.1 mm is measured to determine λ 5 (wavelength at 5% transmittance), λ 70 (wavelength at 70% transmittance) and λ 80 (Wavelength at which the transmittance is 80%).

[0191] [Table 1]

[0192]

[0193] [Table 2]

[0194]

[0195] The specific gravity of the optical glass of the example of the present invention is 4.80 or less, more specifically, 4.50 or less. On the other hand, the specific gravity of the glass of Comparative Example A is greater than 4.80. Therefore, it is shown that the optical glass of the example of the present invention has a smaller specific gravity than the glass of the comparative example.

[0196] The λ of the optical glass of the embodiment of the present invention is 80 (wavelength at which the transmittance is 80%) is 500 nm or less, and more specifically, 480 nm or less. 70 (wavelength at a transmittance of 70%) is 450 nm or less, more specifically, 430 nm or less. 5 (Wavelength at a transmittance of 5%) is 400 nm or less, and more specifically, 380 nm or less.

[0197] In addition, the refractive index (n d ) are all greater than 1.75, and more specifically, greater than 1.80, which is within the desired range.

[0198] In addition, the Abbe number (ν d ) are all greater than 30, more specifically, greater than 35, and the Abbe number (ν d ) is 40 or less, and more specifically, is 39.5 or less, which is within the desired range.

[0199] In addition, the optical glass of the embodiment of the present invention has Nb 2 O 5 Composition and WO 3 The content is small, so the material cost can be reduced.

[0200] Therefore, it is shown that the refractive index (n d ) and Abbe number (ν d ) is within the desired range, can be cheaply produced, has a small specific gravity, is less colored, and has a high visible light transmittance. Therefore, it can be inferred that the optical glass of the embodiments of the present invention contributes to the lightweighting of optical equipment and can be suitably used for the purpose of making visible light permeable.

[0201] In addition, the optical glass of the embodiment of the present invention is subjected to reheating and press molding, and then is ground and polished to be processed into the shape of a lens or a prism. In addition, the optical glass of the embodiment of the present invention is formed into a preform for precision press molding, and the preform for precision press molding is precision press molded into the shape of a lens or a prism. In either case, there is no problem of melting and sticking to the molding die, and there is no problem of milky whitening and devitrification in the heated and softened glass, and various lens and prism shapes can be stably processed.

[0202] The present invention has been described in detail above for the purpose of illustration. However, the present embodiment is for illustrative purposes only, and it should be understood that a person skilled in the art may make various changes without departing from the spirit and scope of the present invention.

Claims

1. An optical glass, characterized in that: The optical glass comprises, by mass%, 17.0 to 35.0% of B2O3, 20.0 to 41.58% of La2O3, 5.0 to 20.0% of TiO2, more than 4.0% and less than 15.0% of SiO2, less than 3.0% of Nb2O5, less than 3.0% of WO3, less than 0.1% of Ta2O5, and less than 6.00% of ZrO2. The optical glass has a refractive index n of not less than 1.80 and not more than 1.

835. d , Abbe number ν of 35 to 37.33 d and a specific gravity below 4.80, The mass sum of the Ln2O3 components is 20.0% or more and 41.58% or less. In the Ln2O3 formula, Ln is at least one selected from La, Gd, Y, and Yb. In terms of mass ratio, (Nb2O5+WO3) / (La2O3+Gd2O3+Ta2O5) is less than 0.

05.

2. The optical glass according to claim 1, characterized in that: By mass, (La2O3+Gd2O3+Ta2O5) is 25.0~41.58%.

3. The optical glass according to claim 1 or 2, characterized in that: In terms of mass ratio, ZnO / BaO is greater than 0 and not more than 5.

0.

4. The optical glass according to claim 1 or 2, characterized in that: By mass, (Nb2O5+WO3+TiO2) is 6.0~20.0%.

5. The optical glass according to claim 1 or 2, wherein: In terms of mass %, Gd2O3 content is 0~20.0%, Y2O3 content is 0~20.0%, Yb2O3 content is 0~10.0%, The Lu2O3 content is 0 to 5.0%.

6. The optical glass according to claim 1 or 2, wherein: In terms of mass %, The CaO content is 0 to 15.0%, BaO content is 0 to 15.0%, MgO content is 0-10.0%, The SrO content is 0 to 10.0%, The ZnO content is 0 to 25.0%.

7. The optical glass according to claim 1 or 2, wherein: The mass sum of the RO components is 30.0% or less, and in the RO formula, R is one or more selected from Mg, Ca, Sr, and Ba.

8. The optical glass according to claim 1 or 2, wherein: In terms of mass %, Li2O content is 0~5.0%, Na2O content is 0~5.0%, The K2O content is 0 to 5.0%.

9. The optical glass according to claim 1 or 2, wherein: The mass sum of Rn2O components is less than 5.0%, and in the Rn2O formula, Rn is one or more selected from Li, Na, and K.

10. The optical glass according to claim 1 or 2, wherein: In terms of mass %, P2O5 content is 0~10.0%, GeO2 content is 0~10.0%, Bi2O3 content is 0~10.0%, TeO2 content is 0~5.0%, Al2O3 content is 0~5.0%, Ga2O3 content is 0~5.0%, SnO content is 0-3.0%, The Sb2O3 component is 0 to 3.0%.

11. The optical glass according to claim 1 or 2, wherein: Spectral transmittance shows 70% at wavelength λ 70 Below 450nm. 12 . A preform for grinding and / or precision press molding, which is formed of the optical glass according to claim 1 . 13 . An optical element formed by grinding and / or polishing the optical glass according to claim 1 .

14. An optical element formed by precision press-molding the preform according to claim 12.

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