Optical glass, preforms and optical elements

Abstract

To provide an optical glass that has desired optical properties, excellent chemical durability, high hardness, and excellent reheat press moldability.SOLUTION: An optical glass contains, on an oxide basis, in mass%, La2O3 component of 8.0% or more, Li2O component of 8.0% or less, and Al2O3 component, with the mass ratio SiO2 / B2O3 of 1.0 or more and 5.0 or less, wherein the refractive index (nd) is 1.70000 or more and 1.80000 or less, the Abbe number (νd) is 45.00 or more and 55.00 or less, and the acid resistance by powder method is 1-3 grades, and the Knoop hardness is 6-7 grades.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In addition to digital cameras, projectors, and security cameras, optical glass is increasingly being used as an optical element such as an imaging lens mounted on an in-vehicle camera as autonomous driving technology advances. For in-vehicle cameras, for example, in applications where the camera is used outdoors, it is common to provide a cover glass or a coating surface on the outermost surface of the glass, but at the same time, the chemical durability of the lens itself is required. Good chemical durability makes it difficult for fogging to occur due to corrosion of the lens surface, enabling long-term use. In addition, in-vehicle cameras are scratched by collisions with dust in the atmosphere or pebbles caught in tires, so optical glass that is resistant to scratches due to impact is required.

[0003] Known methods for producing optical elements from optical glass include, for example, a method of grinding and polishing a gob or glass block formed from optical glass to obtain the shape of an optical element, a method of reheating and molding a gob or glass block formed from optical glass (reheat press molding) to grind and polish a glass molded body obtained, and a method of molding a preform material obtained from a gob or glass block with a highly precisely machined mold (precision mold press molding) to obtain the shape of an optical element. In any method, it is required that a stable glass is obtained when a gob or glass block is formed from molten glass raw material. Here, if the stability against devitrification (devitrification resistance) of the glass constituting the obtained gob or glass block is reduced and crystals are generated inside the glass, it is no longer possible to obtain a glass suitable for an optical element.

[0004] As a lens glass material for vehicle-mounted cameras, it has a refractive index (n d ) and Abbe number (ν dThere is a great demand for glass materials that combine the optical properties of 100 nm with excellent chemical durability and mechanical properties such as Knoop hardness.

[0005] Glass compositions as typified by, for example, Patent Documents 1 to 4 are known as materials used for on-vehicle optical devices. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2018 / 003719 publication [Patent Document 2] JP 2019-194138 A [Patent Document 3] WO2018 / 003720 publication [Patent Document 4] WO2017 / 175552 publication

[0007] However, the optical glasses shown in Patent Documents 1 and 2 are made of SiO 2 B rather than ingredients 2 O 3 Due to the high content of components, acid resistance is poor and the refractive index (n d ) is 1.70000 or more and 1.80000 or less, and the Abbe number (ν d ) does not meet the range of 45.00 to 55.00.

[0008] In addition, the optical glass shown in Patent Document 3 has a refractive index (n d ) is 1.70000 or more and 1.80000 or less, and the Abbe number (ν d ) does not fall within the range of 45.00 to 55.00, and Li 2 The reheat press moldability is poor due to the high O content.

[0009] Furthermore, the optical glass shown in Patent Document 4 has excellent acid resistance, but TiO 2 Due to the high content of the component, the refractive index (n d) is 1.70000 or more and 1.80000 or less, and the Abbe number (ν d ) does not meet the range of 45.00 to 55.00. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical glass which has desired optical properties, good chemical durability, high hardness, and good reheat press moldability.

[0011] More specifically, the refractive index (n d ) and Abbe number (ν d ) and has acid resistance of Class 1 to 3, Knoop hardness of Class 6 or 7, while still having good reheat press moldability. [Means for solving the problem]

[0012] In order to solve the above problems, the present inventors have conducted extensive research and experimentation, and have found that 2 O 3 SiO than the component 2 Increase the content of ingredients and La 2 O 3 Component, Y 2 O 3 Ingredients, Al 2 O 3 The inventors have found that by adjusting the contents of each component, including the component, it is possible to prepare a glass material that has the desired optical properties, good chemical durability and mechanical properties, and good reheat press moldability, and have thus completed the present invention. Specifically, the present invention provides the following.

[0013] (1) Mass percent based on oxides: La 2 O 3 Ingredients: 8.0% or more Li 2O content is 8.0% or less, Al 2 O 3 Contains the ingredients, Mass ratio SiO 2 / B 2 O 3 is between 1.0 and 5.0, and Refractive index (n d ) is between 1.70000 and 1.80000, Abbe number (ν d ) is between 45.00 and 55.00, Acid resistance by powder method: Class 1 to 3 An optical glass with a Knoop hardness of 6 to 7.

[0014] (2) The optical glass according to (1), wherein the RO component is 8.0% or less (R is one or more selected from the group consisting of Mg, Ca, Sr and Ba).

[0015] (3) Mass ratio (Li 2 O×10 3 ) / (Al 2 O 3 +SiO 2 ) is 45.0 or less The optical glass according to (1) or (2),

[0016] (4) An optical element made of the optical glass according to any one of (1) to (3).

[0017] (5) A preform for polishing and / or precision press molding, which is made of the optical glass according to any one of (1) to (4).

[0018] According to the present invention, it is possible to obtain an optical glass having desired optical properties, excellent chemical durability, resistance to impacts, etc., and good reheat press moldability, as well as a preform and an optical element using the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 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 practiced with appropriate modifications within the scope of the object of the present invention. Note that, where the explanation overlaps, the explanation may be omitted as appropriate, but this does not limit the gist of the invention.

[0020] [Glass components] The composition range of each component constituting the optical glass of the present invention is described below. In this specification, the content of each component is expressed as mass% relative to the total mass of the composition converted into oxides, unless otherwise specified. Here, the "composition converted into oxides" refers to a composition that expresses each component contained in the glass, assuming that the oxides, composite salts, metal fluorides, etc. used as raw materials for the glass components of the present invention are all decomposed and converted into oxides during melting, with the total mass number of the generated oxides being 100 mass%.

[0021] <Required and optional ingredients> La 2 O 3 The La component is an essential component for increasing the refractive index and Abbe number of the glass while improving the devitrification resistance. 2 O 3 The lower limit of the content of the component is preferably 8.0% or more, more preferably 10.0% or more, and even more preferably 11.0% or more. On the other hand, La 2 O 3 By setting the content of this component to 50.0% or less, the stability of the glass can be increased and deterioration of acid resistance can be suppressed, so the upper limit is preferably set to 50.0% or less, more preferably 48.0% or less, and even more preferably 47.0% or less.

[0022] SiO 2 The SiO component is a network-forming component and is an essential component for improving the acid resistance and hardness of the glass while enhancing the reheat press moldability. 2 The content of the component is preferably 7.0% or more, more preferably 9.0% or more, and further preferably 10.0% or more. On the other hand, SiO 2By keeping the content of the component at 30.0% or less, the stability of the glass is increased and the decrease in the refractive index is suppressed. 2 The upper limit of the content of the component is preferably 30.0% or less, more preferably 28.0%, even more preferably 27.5% or less, and most preferably 27.0% or less.

[0023] B 2 O 3 The component is a network-forming component and is an essential component for improving the hardness of glass and enhancing reheat press moldability. 2 O 3 The content of the component is preferably 1.0% or more, more preferably 1.5% or more, and further preferably 2.0% or more. On the other hand, B 2 O 3 By keeping the content of the component at 25.0% or less, it becomes easier to obtain a larger refractive index and also prevents deterioration of acid resistance. 2 O 3 The upper limit of the content of the component is preferably 20.0% or less, more preferably 18.0% or less, more preferably 15.0% or less, and even more preferably 12.0% or less.

[0024] SiO 2 Ingredients and B 2 O 3 It is generally accepted in the art that the SiO component is a network forming component, and that it has the same effect, particularly in glasses containing a large amount of rare earth oxides. However, as a result of extensive testing and research, the present inventors have found that SiO 2 The content of the ingredient is B 2 O 3 It has been found that the inclusion of a larger amount of B in the present invention improves acid resistance. 2 O 3 Ingredients and SiO 2 The ingredients do not have the same effect.

[0025] Al 2 O 3 The La component is a network-forming component and is an essential component that can improve acid resistance.2 O 3 Al along with the ingredients 2 O 3 By including Al, it is possible to maintain the acid resistance. 2 O 3 The lower limit of the content of the component is preferably 3.0% or more, more preferably 5.0% or more, and even more preferably 5.8% or more. On the other hand, Al 2 O 3 By keeping the content of this component at 20.0% or less, the devitrification resistance of the glass can be improved. 2 O 3 The upper limit of the content of the component is preferably 20.0% or less, more preferably 18.5% or less, even more preferably 18.0% or less, and even more preferably 17.0% or less.

[0026] Y 2 O 3 When the content of the component is more than 0.0%, the refractive index and Abbe number of the glass can be increased. 2 O 3 The ingredients are La 2 O 3 Component, Gd 2 O 3 Compared to other components, it has the greatest effect of improving acid resistance, but at the same time, it has the property of reducing the stability of glass. 2 O 3 The lower limit of the content of the component is preferably 0.0% or more, more preferably more than 0.0%, more preferably 8.0% or more, more preferably 10.0% or more, and even more preferably 11.0% or more. On the other hand, Y 2 O 3 The upper limit of the content of the component is preferably 32.0% or less, more preferably 30.0% or less, more preferably 28.0% or less, and even more preferably 26.0% or less.

[0027] Gd 2 O 3 When the content of Gd exceeds 0.0%, it can increase the refractive index of the glass and create a stable glass. 2 O 3The lower limit of the content of the component is preferably 0.0% or more, more preferably more than 0.0%, more preferably 0.5% or more, more preferably 1.0% or more, and even more preferably 1.5% or more. On the other hand, Gd 2 O 3 By keeping the content of the component below 48.0%, the increase in specific gravity can be suppressed. 2 O 3 The upper limit of the content is preferably 48.0% or less, more preferably 45.0% or less, more preferably 40.0% or less, and even more preferably 35.0% or less.

[0028] Yb 2 O 3 The component is capable of increasing the refractive index of glass when contained at more than 0.0%. However, Yb 2 O 3 The raw material cost of this component is high, and if the content is high, the production cost will be high. 2 O 3 The upper limit of the content of the component is preferably 4.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, even more preferably 0.5% or less, and even more preferably 0.1% or less.

[0029] ZrO 2 When the content of ZrO exceeds 0.0%, the decrease in acid resistance is suppressed and the refractive index of the glass is increased. 2 The lower limit of the content of the component is preferably 0.0% or more, more preferably more than 0.0%, more preferably 0.5% or more, more preferably 1.0% or more, and even more preferably 1.5% or more. On the other hand, ZrO 2 By keeping the content of this component at 10.0% or less, it is possible to suppress an increase in specific gravity and a deterioration in acid resistance and devitrification resistance. 2 The upper limit of the content of the component is preferably 10.0% or less, more preferably 8.0% or less, and further preferably 6.0% or less.

[0030] The ZnO component is a component that increases the refractive index and acid resistance and improves the hardness of the glass when contained in an amount of more than 0.0%. Therefore, the lower limit of the content of the ZnO component is preferably 0.0% or more, more preferably more than 0.0%, more preferably 0.1% or more, and even more preferably 0.5% or more. On the other hand, by making the content of the ZnO component 13.0% or less, the decrease in the refractive index of the glass can be suppressed and devitrification due to an excessive decrease in viscosity can be reduced. Therefore, the upper limit of the content of the ZnO component is preferably 13.0% or less, more preferably 10.0% or less, more preferably 9.0% or less, and even more preferably 8.0% or less.

[0031] Li 2 O component, Na 2 O component and K 2 The O component is a component that can improve the meltability of glass when contained in an amount exceeding 0.0%. On the other hand, Li 2 O component, Na 2 O component and K 2 By keeping each of the O components at 8.0% or less, the deterioration of reheat press moldability can be suppressed. 2 O component, Na 2 O component and K 2 The upper limit of the O content is preferably 8.0% or less, more preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.5% or less, and most preferably 0.7% or less.

[0032] The MgO component is a component that can improve the melting property of glass raw materials and the devitrification resistance of glass. On the other hand, by keeping the content of the MgO component at 8.0% or less, it is possible to prevent a decrease in refractive index and a decrease in devitrification resistance due to an excessive content. Therefore, the upper limit of the content of the MgO component is preferably 8.0% or less, more preferably 6.5% or less, more preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.5% or less, and most preferably 0.7% or less.

[0033] The CaO component is a component that can increase the hardness of the glass and the meltability of the glass raw material. On the other hand, by keeping the CaO content at 8.0% or less, the decrease in refractive index and the decrease in devitrification resistance due to excessive content can be suppressed. Therefore, the upper limit of the CaO content is preferably 8.0% or less, more preferably 6.5% or less, more preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.5% or less, and most preferably 0.7% or less.

[0034] The SrO component is a component that can improve the melting property of glass raw materials and the devitrification resistance of glass. On the other hand, by keeping the content of the SrO component at 8.0% or less, it is possible to prevent a decrease in the refractive index and a decrease in devitrification resistance due to an excessive content. Therefore, the upper limit of the content of the SrO component is preferably 8.0% or less, more preferably 6.5% or less, more preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.5% or less, and most preferably 0.7% or less.

[0035] The BaO component is a component that can increase the refractive index and Abbe number of the glass when the content exceeds 0.0%. On the other hand, by keeping the content of BaO component at 8.0% or less, it is possible to prevent a decrease in refractive index and deterioration of acid resistance due to the excessive content of these components. Therefore, the upper limit of the content of BaO component is preferably 8.0% or less, more preferably 6.5% or less, more preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.5% or less, and most preferably 0.7% or less.

[0036] TiO 2 Ingredients and Nb 2 O 5 When the content exceeds 0.0%, TiO increases the refractive index of the glass while decreasing the Abbe number. 2 Ingredients and / or Nb 2 O 5 If the component is contained in excess, the Abbe number becomes too small, making it difficult to obtain the desired refractive index and Abbe number. 2 Ingredients and Nb 2 O 5The upper limit of each of the component contents is preferably 8.0% or less, more preferably 5.0% or less, more preferably 2.0% or less, even more preferably 1.5% or less, and most preferably 1.0% or less.

[0037] WO 3 The WO component is a component that, when contained in an amount of more than 0.0%, can increase the refractive index and improve resistance to devitrification while reducing the coloring of the glass caused by other high refractive index components. 3 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0038] Ta 2 O 5 The component is a component that, when contained in an amount of more than 0.0%, can increase the refractive index of the glass and can also increase the resistance to devitrification. 2 O 5 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0039] P 2 O 5 The component is a component that, when contained in an amount of more than 0.0%, can lower the liquidus temperature of the glass and increase the resistance to devitrification. 2 O 5 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0040] GeO 2 The component is a component that can increase the refractive index of the glass and improve the devitrification resistance when contained in an amount exceeding 0.0%. GeO 2 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0041] Ga 2 O 3The Ga component is a component that can improve the chemical durability of glass and the devitrification resistance of molten glass when contained in an amount of more than 0.0%. 2 O 3 The upper limit of the content of the component is 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0042] Bi 2 O 3 The Bi component is a component that can increase the refractive index and lower the glass transition point when contained in an amount of more than 0.0%. 2 O 3 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0043] TeO 2 The component is a component that can increase the refractive index and lower the glass transition point when contained in an amount of more than 0.0%. TeO 2 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0044] SnO 2 This component, when contained in an amount of more than 0.0%, reduces the oxidation of the molten glass, thereby clarifying it, and also increases the visible light transmittance of the glass. 2 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0045] The F component is a component that can improve the meltability of glass when contained in an amount exceeding 0.0%, but on the other hand, a high content of the F component leads to devitrification due to volatilization of the F component. The upper limit of the F component content is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less.

[0046] Sb 2 O 3The component is capable of degassing the molten glass when contained in an amount of more than 0.0%. On the other hand, Sb 2 O 3 If the content of Sb is too high, the transmittance in the short wavelength region of the visible light range will be poor. 2 O 3 The upper limit of the content of the component is preferably 1.0% or less, more preferably 0.5% or less, and further preferably 0.3% or less.

[0047] The component that clarifies and defoams the glass is the above-mentioned Sb 2 O 3 There is no limitation on the components, and any fining agent, defoaming agent or combination thereof known in the art of glass manufacturing can be used.

[0048] Ln 2 O 3 When the sum of the contents (sum of mass) of the components (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) is 40.0% or more, the refractive index can be increased while the Abbe number is increased. 2 O 3 The lower limit of the sum of the components is preferably 40.0% or more, more preferably 42.0% or more, even more preferably 45.0% or more, and even more preferably 47.5% or more. On the other hand, Ln 2 O 3 By setting the sum of the contents of the components (sum of mass) to 65.0% or less, devitrification due to excessive content can be reduced. Therefore, the upper limit is preferably set to 65.0% or less, more preferably 62.0% or less, and further preferably 60.0% or less.

[0049] Rn 2 The O component (wherein Rn is one or more selected from the group consisting of Li, Na and K) can improve the meltability of the glass when the sum of the contents (sum of mass) exceeds 0.0%. On the other hand, Rn 2 By setting the sum of the contents (mass sum) of the O components to 8.0% or less, the deterioration of reheat press moldability can be suppressed. 2The O component is SiO 2 When Rn is contained in the glass, it tends to cause devitrification. Therefore, in the present invention, the content of Rn is preferably small. 2 The upper limit of the sum of the contents of O components (sum of mass) is preferably 8.0% or less, more preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.5% or less, and most preferably 1.0% or less.

[0050] When the sum of the contents of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is more than 0.0%, the meltability can be improved. However, the RO component is SiO 2 Since RO components tend to cause devitrification when contained together with other components, it is preferable that the content is small in the present invention. Therefore, the upper limit of the sum of the masses of RO components is preferably 8.0% or less, more preferably 6.5% or less, more preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.5% or less, and most preferably 0.7% or less.

[0051] B 2 O 3 SiO relative to components 2 The mass ratio of the components is SiO 2 / B 2 O 3 By setting the SiO content to 1.0 or more and 5.0 or less, the acid resistance can be improved and the hardness of the glass can be increased. 2 Ingredients and B 2 O 3 It is generally accepted in the art that the SiO component is a network forming component, and that it has the same effect, particularly in glasses containing a large amount of rare earth oxides. However, as a result of extensive testing and research, the present inventors have found that SiO 2 The content of the ingredient is B 2 O 3 By containing more of it than the B component, the hardness of the glass is increased. 2 O 3 They discovered that this has the effect of suppressing the deterioration of acid resistance caused by the ingredients. Therefore, the mass ratio SiO 2 / B 2 O3 The lower limit of is preferably 1.0 or more, more preferably 1.2 or more, even more preferably 1.3 or more, and most preferably 1.5 or more. On the other hand, the mass ratio SiO 2 / B 2 O 3 The upper limit of is preferably 5.0 or less, more preferably 4.8 or less, even more preferably 4.3 or less, still more preferably 3.8 or less, and most preferably 3.5 or less.

[0052] SiO 2 Ingredients, B 2 O 3 Ingredients, Al 2 O 3 Al relative to the total amount of components 2 O 3 The mass ratio of the components is Al 2 O 3 / (SiO 2 +B 2 O 3 +Al 2 O 3 ) is preferably 0.05 to 0.50. The present invention relates to Si-La based glass, but the rare earth oxide is Al. 2 O 3 Ingredients and SiO 2 Ingredients, B 2 O 3 Since its acid resistance is inferior to that of the other components, the mass ratio of Al 2 O 3 / (SiO 2 +B 2 O 3 +Al 2 O 3 ) in the range of 0.05 to 0.50 can improve the acid resistance while enhancing the devitrification resistance. Therefore, the mass ratio Al 2 O 3 / (SiO 2 +B 2 O 3 +Al 2 O 3 ) is preferably 0.05 or more, more preferably 0.08 or more, even more preferably 0.12 or more, and most preferably 0.15 or more. On the other hand, the mass ratio Al 2 O 3 / (SiO 2 +B 2 O 3 +Al 2 O 3 ) is preferably 0.50 or less, more preferably 0.45 or less, even more preferably 0.40 or less, still more preferably 0.35 or less, and most preferably 0.30 or less as an upper limit.

[0053] Al 2 O 3 Components and SiO 2 Li relative to the total amount of components 2 The mass ratio (Li 2 O×10 3 ) / (Al 2 O 3 +SiO 2 ) is preferably 45.0 or less. Li 2 The O component improves melting properties, but it also deteriorates reheat press moldability. In particular, when Li-Al-Si-O components are contained together, crystallization during reheat press molding is likely to occur. Therefore, the mass ratio (Li 2 O×10 3 ) / (Al 2 O 3 +SiO 2 ) to 45.0 or less, the above problem can be solved. Therefore, the mass ratio (Li 2 O×10 3 ) / (Al 2 O 3 +SiO 2 ) is preferably 45.0 or less, more preferably 35.0 or less, even more preferably 25.0 or less, still more preferably 15.0 or less, and most preferably 13.0 or less. On the other hand, the mass ratio (Li 2 O×10 3 ) / (Al 2 O 3 +SiO 2) has a lower limit of preferably 0, more preferably 0.50 or more, even more preferably 0.80 or more, and most preferably 1.00 or more.

[0054] SiO 2 Ingredients and Ln 2 O 3 B relative to the total amount of ingredients 2 O 3 The mass ratio (B 2 O 3 ×10 2 ) / (SiO 2 +Ln 2 O 3 By making the refractive index and hardness of the glass improved while suppressing deterioration of the acid resistance, the refractive index and hardness of the glass can be improved by making the refractive index and hardness of the glass improved. Therefore, the mass ratio (B 2 O 3 ×10 2 ) / (SiO 2 +Ln 2 O 3 ) is preferably 5.0 or more, more preferably 6.0 or more, even more preferably 8.0 or more, and most preferably 10.0 or more. On the other hand, the mass ratio (B 2 O 3 ×10 2 ) / (SiO 2 +Ln 2 O 3 ) is preferably 20.0 or less, more preferably 18.0 or less, even more preferably 16.0 or less, and most preferably 14.0 or less.

[0055] <Ingredients that should not be included> Next, components that should not be contained in the optical glass of the present invention and components whose inclusion is undesirable will be described.

[0056] Other components may be added as necessary within the range that does not impair the characteristics of the glass of the present invention. However, each transition metal component, such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, except for Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, has the property that the glass is colored and absorbs specific wavelengths in the visible range even when contained alone or in combination in small amounts, so it is preferable that it is not substantially contained, especially in optical glasses that use wavelengths in the visible range. Also, it is preferable that each component, Rb and Cs, is not contained from the viewpoint of suppressing coloration of the glass.

[0057] In addition, lead compounds such as PbO and As 2 O 3 Since arsenic compounds such as those mentioned above are components that have a high environmental impact, it is desirable that they are not substantially contained, that is, that they are not contained at all except for unavoidable contamination.

[0058] Furthermore, in recent years, there has been a trend to refrain from using the components Th, Cd, Tl, Os, Be, and Se as harmful chemical substances, and environmental measures are required not only in the glass manufacturing process but also in the processing process and disposal after commercialization. Therefore, when environmental impact is important, it is preferable that these components are not substantially contained.

[0059] [Manufacturing method] The optical glass of the present invention is produced, for example, as follows: High purity raw materials used for ordinary optical glass, such as oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphate compounds, are mixed uniformly as the raw materials for each of the above components so that each component falls within a prescribed content range, the mixture is charged into a platinum crucible, and melted in an electric furnace at a temperature range of 1100 to 1400°C for 1 to 5 hours depending on the melting difficulty of the glass raw materials, stirred and homogenized, and then cooled to an appropriate temperature, cast into a mold, and slowly cooled to produce the glass.

[0060] <Physical Properties> The optical glass of the present invention has desired optical properties. The refractive index (n d) is preferably 1.70000 or more, more preferably 1.72000 or more, and even more preferably 1.73000 or more as the lower limit. d ) is preferably 1.80000 or less, more preferably 1.78000 or less, and more preferably 1.76000 or less. In addition, the Abbe number (ν d ) is preferably 45.00 or more, more preferably 46.00 or more, and even more preferably 47.00 or more. d ) is preferably 55.00 or less, more preferably 53.00 or less, and even more preferably has an upper limit of 51.00 or less.

[0061] The acid resistance of the glass in the examples and comparative examples is measured in accordance with the Japan Optical Glass Industry Association standard "Method of measuring chemical durability of optical glass" JOGIS06-2006. That is, a glass sample crushed to a particle size of 425 to 600 μm was placed in a pycnometer and placed in a platinum cage. The platinum cage was placed in a quartz glass round-bottom flask containing a 0.01N aqueous solution of nitric acid, and treated in a boiling water bath for 60 minutes. The weight loss rate (mass%) of the glass sample after treatment was calculated, and the weight loss rate (mass%) of less than 0.20 was classified as Class 1, the weight loss rate of 0.20 to less than 0.35 was classified as Class 2, the weight loss rate of 0.35 to less than 0.65 was classified as Class 3, the weight loss rate of 0.65 to less than 1.20 was classified as Class 4, the weight loss rate of 1.20 to less than 2.20 was classified as Class 5, and the weight loss rate of 2.20 or more was classified as Class 6. In this case, the smaller the class number, the better the acid resistance of the glass. In the optical glass of the present invention, it is preferably class 1 to 3, and more preferably class 1 to 2.

[0062] The optical glass of the present invention preferably has a Knoop hardness of at least Class 6 when measured according to the method of measurement in accordance with "JOGIS09-1975 Method for Measuring Knoop Hardness of Optical Glass". This makes it difficult for scratches or breaks to occur during polishing of the glass, and scratches to the surface during transportation of the glass, etc., and therefore makes it possible to obtain optical glass that has a desired surface condition and that is easy to maintain that surface condition. Therefore, the Knoop hardness of the optical glass of the present invention is preferably Class 6, and more preferably Class 7.

[0063] [Preforms and optical elements] From the produced optical glass, a glass molded body can be produced, for example, by using a polishing means or a mold press molding means such as reheat press molding or precision press molding. That is, a glass molded body can be produced by performing mechanical processing such as grinding and polishing on the optical glass, a preform for mold press molding can be produced from the optical glass, and the preform can be subjected to reheat press molding and then polished to produce a glass molded body, or a preform produced by polishing or a preform molded by known floating molding can be subjected to precision press molding to produce a glass molded body. Note that the means for producing a glass molded body are not limited to these means.

[0064] Thus, the optical glass of the present invention is useful for various optical elements and optical designs. In particular, it is preferable to form a preform from the optical glass of the present invention and use the preform to perform reheat press molding, precision press molding, or the like to produce optical elements such as lenses and prisms. This makes it possible to form a preform with a large diameter, so that while the optical element can be made larger, high-definition and high-precision imaging and projection characteristics can be achieved when used in optical equipment.

[0065] The glass molded article made of the optical glass of the present invention can be used for optical elements such as lenses, prisms, and mirrors, and can also be used for applications requiring good hardness and chemical durability, such as in-vehicle optical instruments such as in-vehicle cameras. EXAMPLES

[0066] The compositions of the examples (No. 1 to No. 70) of the present invention and the comparative examples A and B, as well as the refractive index (n d ), Abbe number (ν d The results of the test pieces were measured for hardness (hardness), chemical durability (acid resistance) by the powder method, and Knoop hardness, and are shown in Tables 1 to 4. Note that the following examples are merely for illustrative purposes, and the present invention is not limited to these examples.

[0067] For the glasses of the examples of the present invention, high-purity raw materials used in ordinary optical glass, such as the corresponding oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphate compounds, were selected as the raw materials for each component, and were weighed out and mixed uniformly to obtain the composition ratios of each example and comparative example shown in the table. The mixture was then placed in a quartz crucible or a platinum crucible and melted in an electric furnace at a temperature range of 1100 to 1400°C for 1 to 5 hours depending on the melting difficulty of the glass composition. After stirring and homogenizing the mixture and removing bubbles, the temperature was lowered to 1000 to 1300°C and the mixture was stirred and homogenized, and the mixture was poured into a mold and slowly cooled to produce the glass.

[0068] The refractive index (n d ), Abbe number (ν d ) was measured according to the V-block method specified in JIS B 7071-2:2018. Here, the refractive index (n d ) is shown as a measurement value for the d line (587.56 nm) of a helium lamp. d ) is the refractive index for the d line of the helium lamp (n d ) and the refractive index (n F ), and the refractive index for the C line (656.27 nm) (n C ) value, the Abbe number (ν d )=[(n d -1) / (n F -n C The refractive indexes (n d ), Abbe number (ν d) was determined by measuring the glass obtained by cooling at a rate of -25°C / hr.

[0069] The chemical durability of the glass in the examples and comparative examples was measured in accordance with the Japan Optical Glass Industry Association standard "Method of measuring the chemical durability of optical glass" JOGIS06-2006. That is, a glass sample crushed to a particle size of 425 to 600 μm was placed in a pycnometer and placed in a platinum cage. The platinum cage was placed in a quartz glass round-bottom flask containing a 0.01N aqueous solution of nitric acid, and treated in a boiling water bath for 60 minutes. The weight loss rate (mass%) of the glass sample after treatment was calculated, and the weight loss rate (mass%) of less than 0.20 was classified as Class 1, the weight loss rate of less than 0.20 to 0.35 was classified as Class 2, the weight loss rate of less than 0.35 to 0.65 was classified as Class 3, the weight loss rate of less than 0.65 to 1.20 was classified as Class 4, the weight loss rate of less than 1.20 to 2.20 was classified as Class 5, and the weight loss rate of 2.20 or more was classified as Class 6. In this case, the smaller the class number, the better the acid resistance of the glass.

[0070] The Knoop hardness (Hk) of the glasses in the examples and comparative examples was measured based on the standard of the Japan Optical Glass Industry Association (JOGIS09-1975). Specifically, a diamond rhombus indenter (with diagonal angles of 172°30' and 130°) was pressed against the flat polished surface of the sample with a load of 0.98 N (0.1 kgf) for 15 seconds to make an indentation, and the length of the longer diagonal of the indentation was measured and calculated using formula (1).

[0071] Knoop hardness = 1.451F / l 2 (1) F: Load (N) l: Length of the longer diagonal (mm) Knoop hardness is classified as grade 1 when it is less than 150, grade 2 when it is 150 or more but less than 250, grade 3 when it is 250 or more but less than 350, grade 4 when it is 350 or more but less than 450, grade 5 when it is 450 or more but less than 550, grade 6 when it is 550 or more but less than 650, and grade 7 when it is 650 or more. The higher the grade, the harder the glass.

[0072] [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] [Table 4]

[0076] As shown in the table, the optical glasses of the examples all have a refractive index (n d The Abbe number (ν d ) was within the range of 45.00 to 55.00.

[0077] Furthermore, the optical glasses of the examples were found to be in Class 1 to 3 in terms of chemical durability (acid resistance) according to the powder method, and were found to be glasses that were less prone to fogging and could be used for a long period of time.

[0078] Furthermore, the optical glasses according to the examples of the present invention had Knoop hardness of class 6 to 7. This made it clear that the optical glasses according to the examples of the present invention were hard glasses.

[0079] Furthermore, a glass block was formed using the optical glass of the embodiment of the present invention, and the glass block was ground and polished to be processed into the shapes of lenses and prisms. As a result, it was possible to stably process the glass block into various shapes of lenses and prisms.

[0080] Although the present invention has been described in detail for purposes of illustration, it will be understood that the present embodiments are for illustrative purposes only and that numerous modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. In mass% based on oxide, La 2 O 3 Ingredients: 8.0% to 47.0% SiO 2 Ingredients: 16.69% or more B 2 O 3 Ingredients: 6.21% or more A 2 O 3 Ingredients: 7.27% to 14.02% Contains ZrO 2 Ingredients are 6.0% or less, ZnO content is 8.0% or less, Ln 2 O 3 The sum of the contents of the components is 51.20% or more (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb); Rn 2 The sum of the contents of O components is 1.5% or less (wherein Rn is one or more selected from the group consisting of Li, Na, and K); The sum of the contents of RO components is 5.0% or less (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba); Mass ratio SiO 2 / B 2 O 3 is 1.92 or more and 5.0 or less and Refractive index (n ｄ ) is between 1.72000 and 1.80000, Abbe number (ν ｄ ) is between 45.00 and 55.00, Acid resistance by powder method is 1st to 3rd grade. An optical glass with a Knoop hardness of 6 to 7.

2. Mass ratio (Li 2 O x 10 3 ) / (Al 2 O 3 +SiO 2 ) is 45.0 or less 2. The optical glass according to claim 1,

3. 3. An optical element comprising the optical glass according to claim 1 or 2.

4. A preform for polishing and / or precision press molding, comprising the optical glass according to claim 1 or 2.

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