Optical glass and optical elements

Abstract

To provide an optical glass having high stability while having a low specific gravity relative to its refractive index and to provide an optical element.SOLUTION: A glass contains, in mass% on an oxide basis, an Ln2O3 component of 10.0% or less (Ln is at least one selected from a group consisting of La, Y, Gd, and Yb), with a mass ratio TiO2 / RO of 0.5 or more and 1.5 or less (R is at least one selected from a group consisting of Mg, Ca, Sr, and Ba), a total mass Nb2O5+WO3+Bi2O3 of 18.0% or less, and a mass ratio BaO / RO of 0.30 or more and 0.95 or less. With a specific gravity as d and a refractive index as nd, a relationship of d≤6.17×nd-7.694 is satisfied in the glass.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Optical glass and optical elements can be used in applications such as combining lenses of different optical regions to improve the optical characteristics of cameras and imaging devices, and incorporating them into optical equipment to realize various optical designs. In particular, reducing the weight of optical glass and optical elements leads to more compact and lightweight optical device bodies, modules, etc. For example, in photographic devices such as digital cameras, it is possible to correct chromatic aberration by combining multiple lenses, and in cameras with zoom and autofocus functions, lightweight optical elements enable smoother transmission of power between the actuator and the lens, improving performance.

[0003] On the other hand, as glasses with a high refractive index, La-based glasses described in Patent Document 1 and P-Nb-based glasses described in Patent Document 2 are known, and Patent Documents 3 and 4 describe inventions that focus on reducing the weight of optical devices. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-035037 A [Patent Document 2] JP 2012-171848 A [Patent Document 3] WO2018 / 235725 publication [Patent Document 4] JP 2006-219365 A Summary of the Invention [Problem to be solved by the invention]

[0005] The glass disclosed in Patent Document 1 contains a large amount of rare earth oxides, which have a high specific gravity compared to other components, while Patent Document 2 contains a large amount of Nb, which is one of the components that has a high refractive index effect and increases the specific gravity. Components that have a large effect of increasing the refractive index include rare earth oxides and TiO 2 Component, Nb 2 O 5 Ingredients: WO 3 Ingredients: Bi 2 O 3 The ingredients are given.

[0006] In order to obtain an optical glass with a high refractive index, it is necessary to increase the content of the above components, but these components all have a large specific gravity compared to other components. Among the above components, TiO 2 The component with the smallest specific gravity is TiO 2 While the component has a low specific gravity, it also reduces stability and is prone to causing devitrification.

[0007] In producing glass, the specific gravity tends to increase as the refractive index increases by increasing the content of components that increase the refractive index. The glass disclosed in Patent Document 3 has a large specific gravity compared to the refractive index, so it cannot be said that the weight of the optical glass is sufficiently reduced. Furthermore, the glass disclosed in Patent Document 4 has a refractive index (n d ) as Y and the glass specific gravity as X. The objective is to obtain glass with a low specific gravity relative to its refractive index by satisfying Y ≥ 0.175X + 1.137.

[0008] The present invention has been made in view of the above problems, and an object of the present invention is to obtain a glass which has a low specific gravity relative to its refractive index and is highly stable. [Means for solving the problem]

[0009] In order to solve the above problems, the present inventors have conducted extensive research and experimentation, and have found that rare earth oxides and Nb 2 O 5 Ingredients: WO 3 Ingredients: Bi2 O 3 The content of the component is reduced, and TiO 2 The content of the components and RO components is adjusted to make the specific gravity d and the refractive index n. d Then, d≦6.17×n d The inventors discovered that by achieving the relationship of -7.694, it is possible to obtain a glass that has a low specific gravity relative to its refractive index and is highly stable, and have thus completed the present invention. Specifically, the present invention provides the following:

[0010] (1) Mass percent on an oxide basis: Ln 2 O 3 Component is 10.0% or less (Ln is one or more selected from the group consisting of La, Y, Gd, and Yb), Mass ratio TiO 2 / RO is 0.5 or more and 1.5 or less (R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba), Mass sum Nb 2 O 5 +WO 3 +Bi 2 O 3 is 18.0% or less, The mass ratio BaO / RO is 0.30 or more and 0.95 or less, and Specific gravity is d and refractive index is n d When d≦6.17×n d Glass that satisfies the relationship -7.694.

[0011] (2) In mass percent on an oxide basis, Nb 2 O 5 Ingredients 0~18.0%, WO 3 Ingredients 0~15.0%, La 2 O 3 Ingredients 0~10.0% The optical glass according to (1),

[0012] (3) The sum of the RO component contents is 20.0% or more The optical glass according to (1) or (2),

[0013] (4) An optical element made of the optical glass according to any one of (1) to (3). Effect of the Invention

[0014] According to the present invention, it is possible to provide an optical glass and an optical element which have a low specific gravity relative to their refractive index and are highly stable. [Brief description of the drawings]

[0015] [Figure 1] This figure shows both an equation showing the relationship of d≦6.17×nd-7.694, where d is the specific gravity of the glass in the examples of the present application and nd is the refractive index, and an equation showing the relationship of Y≧0.175X+1.137, where Y is the refractive index (nd) described in Patent Document 4 and X is the glass specific gravity (hereinafter, sometimes referred to as Y≧0.175X+1.137). The plots shown in Figure 1 are Examples 11, 13, 19, and 22 of JP 2006-219365 A (Patent Document 4).

[0016] [Diagram 2] FIG. 2 is a graph showing the relationship between the specific gravity of the glass in the examples of the present application, d, and the refractive index, nd. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments of the optical glass of the present invention will be described in detail. 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, although explanations of duplicated parts may be omitted as appropriate, this does not limit the gist of the invention.

[0018] [Glass components] The composition range of each component constituting the optical glass of the present invention is described below. Unless otherwise specified in this specification, the content of each component is expressed as mass% relative to the total substance amount of the glass in terms of oxide. Here, "composition in terms of oxide" refers to a composition in which each component contained in the glass is expressed, assuming that oxides, composite salts, metal fluorides, etc. used as raw materials for the glass components of the present invention are all decomposed and converted to oxides during melting, with the total mass of the generated oxides being 100 mass%.

[0019] SiO 2 The component is a component that, when contained at 5.0% or more, promotes stable glass formation and thereby enhances the devitrification resistance of the glass. In particular, SiO 2 By limiting the content of the component to 35.0% or less, SiO 2 The decrease in the refractive index due to the SiO 2 The upper limit of the content of the component is preferably 35.0% or less, more preferably 33.0% or less, even more preferably 30.0% or less, even more preferably 28.0% or less, and most preferably 25.0% or less. 2 The lower limit of the content of the component is preferably 5.0% or more, more preferably 6.0% or more, even more preferably 7.0% or more, and most preferably 8.0% or more.

[0020] TiO 2 The TiO component is an essential component of the present invention, and increases the refractive index and Abbe number of the glass when its content is 21.0% or more. 2 By keeping the content of this component at 40.0% or less, it is possible to suppress devitrification caused by excessive content. 2 The content of the TiO component is preferably 40.0% or less, more preferably 39.0% or less, and most preferably 38.0% or less. 2 The lower limit of the content of the component is preferably 21.0% or more, more preferably 22.0% or more, even more preferably 23.0% or more, still more preferably 24.0% or more, and most preferably 25.0% or more.

[0021] Nb2 O 5 The component, when contained at more than 0%, increases the refractive index and Abbe number of the glass, and TiO 2 It is an optional component that can enhance stability when included with other components. 2 O 5 By making the content of this component 18.0% or less, the specific gravity can be reduced and the devitrification resistance can be improved. 2 O 5 The upper limit of the content of the element is preferably 18.0% or less, more preferably 15.0% or less, more preferably 12.0% or less, more preferably 11.0% or less, and most preferably 10.0% or less. 2 O 5 From the viewpoint of enhancing stability, the content of the component is preferably 1.0% or more, more preferably 2.0% or more, even more preferably 3.0% or more, even more preferably 4.0% or more, and most preferably 5.0% or more, with the lower limit being, however, it may be 0%.

[0022] WO 3 Ingredients: Bi 2 O 3 WO is a component that increases the refractive index of glass when contained at more than 0%, but if the content is too high, it causes coloring of the glass and increases its specific gravity. 3 Ingredients: Bi 2 O 3 The preferred ranges of the ingredients are as follows:

[0023] WO 3 The upper limit of the content of the component is preferably 15.0% or less, more preferably 10.0% or less, more preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less.

[0024] Bi 2 O 3 The upper limit of the component content is preferably 3.0% or less, more preferably 1.0% or less, even more preferably 0.8% or less, even more preferably 0.5% or less, even more preferably 0.3% or less, and most preferably 0.1% or less.

[0025] B2 O 3 The component is an optional component that, when contained in an amount of more than 0%, promotes the formation of stable glass, thereby improving resistance to devitrification. In particular, B 2 O 3 By keeping the content of the ingredient below 20.0%, B 2 O 3 Since the decrease in the refractive index due to the component is suppressed, it is easy to obtain a high refractive index. 2 O 3 The upper limit of the content of the component is preferably 20.0% or less, more preferably 17.0% or less, even more preferably 15.0% or less, and most preferably 12.0% or less. 2 O 3 The lower limit of the content of the component is preferably more than 0%, more preferably 0.5% or more, even more preferably 0.8% or more, and most preferably 1.0% or more, but may be 0%.

[0026] When the BaO component is contained at more than 0%, it is a component that enhances the stability of the glass and improves the workability during polishing and grinding. In particular, the specific gravity can be reduced by making the content of the BaO component 35.0% or less. Therefore, the upper limit of the content of the BaO component is preferably 35.0% or less, more preferably 33.5% or less, and most preferably 32.0% or less. On the other hand, the lower limit of the content of the BaO component is preferably 10.0% or more, more preferably 12.0% or more, even more preferably 14.0% or more, and most preferably 15.0% or more.

[0027] The CaO component is a component that can reduce the specific gravity of the glass when it is contained in an amount exceeding 0%. In particular, by making the CaO component content 15.0% or less, it is possible to improve the devitrification resistance. Therefore, the upper limit of the CaO component content is preferably 15.0% or less, more preferably 14.0% or less, and most preferably 13.0% or less. On the other hand, the lower limit of the CaO component content is preferably 0.5% or more, more preferably 1.0% or more, even more preferably 2.0% or more, and most preferably 3.0% or more, but it may be 0%.

[0028] The MgO and SrO components are components that increase the devitrification resistance of the glass when they are contained at more than 0%, but if the content is too high, it becomes difficult to maintain the refractive index and Abbe number. The preferred ranges of the MgO and SrO components are as follows:

[0029] The upper limit of the content of the MgO component is preferably 10.0% or less, more preferably 7.0% or less, further preferably 5.0% or less, and most preferably 3.0% or less, but may be 0%.

[0030] The upper limit of the SrO content is preferably 10.0% or less, more preferably 7.0% or less, further preferably 5.0% or less, and most preferably 3.0% or less, but may be 0%.

[0031] La 2 O 3 Component, Y 2 O 3 Component, Gd 2 O 3 Ingredients, Yb 2 O 3 When contained at more than 0%, this component increases the refractive index of the glass, reduces the amount of wear on the glass during polishing, and makes the glass less likely to crack, chip, or have poor surface accuracy. However, if the content is too high, the glass loses stability and its specific gravity increases. 2 O 3 Component, Y 2 O 3 Component, Gd 2 O 3 Ingredients, Yb 2 O 3 The preferred ranges of the ingredients are as follows:

[0032] La 2 O 3 The upper limit of the content of the component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, still more preferably 3.0% or less, and most preferably 1.0% or less.

[0033] Y 2 O 3The upper limit of the content of the component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, still more preferably 3.0% or less, and most preferably 1.0% or less.

[0034] Gd 2 O 3 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, still more preferably 1.0% or less, and most preferably 0.5% or less.

[0035] Yb 2 O 3 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, still more preferably 1.0% or less, and most preferably 0.5% or less.

[0036] ZrO 2 The component is an optional component that promotes stable glass formation and improves the devitrification resistance of the glass when contained at more than 0%. 2 By keeping the content of this component below 10.0%, glass processing by polishing, grinding, etc. becomes easier. Therefore, ZrO 2 The upper limit of the content of the component is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 8.0% or less, and most preferably 7.0% or less. 2 The content of the component is preferably 0.1% or more, more preferably 0.2% or more, and even more preferably 0.3% or more, but may be 0%.

[0037] Li 2 O component, K 2 O component, Na 2 The O component is a component that lowers the melting temperature of glass when it is contained in excess of 0%, but if the content is too high, it impairs stability and makes the glass more susceptible to devitrification. 2 O component, K 2 O component, Na 2 The preferred range of the O component is as follows:

[0038] Li2 The upper limit of the O content is preferably 7.0% or less, more preferably 5.0% or less, further preferably 3.0% or less, and most preferably 1.0% or less.

[0039] K 2 The upper limit of the O content is preferably 7.0% or less, more preferably 5.0% or less, further preferably 3.0% or less, and most preferably 1.0% or less.

[0040] Na 2 The upper limit of the content of the O component is preferably 10.0% or less, more preferably 8.0% or less, further preferably 6.0% or less, and most preferably 4.0% or less. 2 The lower limit of the O component content is preferably 0.1% or more, more preferably 0.3% or more, and most preferably 0.5% or more, but may be 0%.

[0041] Al 2 O 3 The component is an optional component that, when contained at more than 0%, improves the chemical durability of the glass while increasing the viscosity of the glass when melted. In particular, Al 2 O 3 By keeping the content of this component at 5.0% or less, the meltability of the glass can be improved while reducing the tendency of the glass to devitrify. 2 O 3 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less, but may be 0%.

[0042] The ZnO component is an optional component that lowers the liquidus temperature of the glass and increases the devitrification resistance of the glass when it is contained in an amount exceeding 0%. In particular, by making the content of the ZnO component 5.0% or less, it is possible to easily obtain a high refractive index and low dispersion. Therefore, the upper limit of the content of the ZnO component is preferably 5.0% or less, more preferably 3.0% or less, and most preferably 1.0% or less, but it may be 0%.

[0043] Ta 2 O5 The Ta component is an optional component that, when contained at more than 0%, increases the refractive index of the glass and increases the devitrification resistance of the glass. 2 O 5 By keeping the content of this ingredient to 5.0% or less, the rare mineral resource Ta 2 O 5 The amount of components used is reduced, and the glass is easier to melt at a lower temperature, which reduces the production costs of the glass. 2 O 5 This can reduce the devitrification of glass caused by the excessive inclusion of Ta 2 O 5 The upper limit of the content of the component is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less, but may be 0%.

[0044] P 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, but may be 0%.

[0045] The upper limit of the F content is preferably 5.0% or less, more preferably 3.0% or less, more preferably 1.0% or less, further preferably 0.5% or less, and further preferably 0.3% or less, but may be 0%.

[0046] TeO 2 The upper limit of the content of the component is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less, but may be 0%.

[0047] GeO 2 The upper limit of the content of the component is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less, but may be 0%.

[0048] CEO 2The upper limit of the content of the component is preferably 3.0% or less, more preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less, but may be 0%.

[0049] Er 2 O 3 Ingredients, Pr 2 O 3 The content of the component is preferably 1.0% or less, more preferably 0.5% or less, more preferably 0.1% or less, and most preferably substantially none is contained.

[0050] SnO 2 The upper limit of the content of the component is preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less, but may be 0%.

[0051] Sb 2 O 3 The Sb component is an optional component that promotes fining and defoaming when the glass is melted. 2 O 3 By keeping the content of Sb to 0.1% or less, it is possible to suppress coloring, especially in high refractive index glass. In addition, by keeping the content of Sb to 0.1% or less, excessive foaming during glass melting is unlikely to occur, so 2 O 3 It is possible to make the components less likely to alloy with the melting equipment (especially precious metals such as Pt). 2 O 3 The upper limit of the content of the component is preferably 0.1% or less, more preferably 0.08% or less, and even more preferably 0.05% or less, but may be 0%.

[0052] 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.

[0053] Ln 2 O 3By setting 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) to 10.0% or less, devitrification due to excessive content can be suppressed and the specific gravity can be reduced. Therefore, the upper limit is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 6.0% or less, even more preferably 4.0% or less, and even more preferably 2.0% or less.

[0054] Rn 2 By setting the sum of the contents of the O component (wherein Rn is one or more selected from the group consisting of Li, Na, and K) to 10.0% or less, the deterioration of reheat press moldability can be suppressed. 2 The upper limit of the sum of the contents of the O components is preferably 10.0% or less, more preferably 9.0% or less, and most preferably 8.0% or less. 2 In order to improve the meltability, the lower limit of the sum of the contents of the O components is preferably 0.5% or more, more preferably 0.8% or more, and even more preferably 1.0% or more, but may be 0%.

[0055] 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%, the stability of the glass can be improved. In particular, the RO component is TiO 2 It has the function of suppressing devitrification due to RO components. The sum of the contents of RO components is preferably 20.0% or more, more preferably 21.5% or more, even more preferably 23.0% or more, and most preferably 25.0% or more. On the other hand, in order to suppress a decrease in the refractive index, the upper limit of the sum of the contents of RO components is preferably 40.0% or less, more preferably 39.0% or less, more preferably 38.0% or less, even more preferably 37.0% or less, and most preferably 36.0% or less.

[0056] TiO for RO components 2 The mass ratio of the components is TiO 2 By setting the / RO to 0.50 or more and 1.50 or less, TiO 2It is possible to produce highly stable glass while suppressing devitrification caused by the components. Producing highly stable glass is useful because it leads to improved mass productivity. Therefore, the mass ratio of TiO 2 The lower limit of / RO is preferably 0.50 or more, more preferably 0.55 or more, even more preferably 0.60 or more, even more preferably 0.65 or more, and most preferably 0.70 or more. 2 The upper limit of / RO is preferably 1.50 or less, more preferably 1.45 or less, even more preferably 1.40 or less, still more preferably 1.35 or less, and most preferably 1.30 or less.

[0057] Nb 2 O 5 Ingredients: WO 3 Ingredients: Bi 2 O 3 The total mass of the components is Nb 2 O 5 +WO 3 +Bi 2 O 3 The increase in specific gravity can be suppressed by keeping the content of Nb at 18.0% or less. Many of the high refractive index contributing components have a higher specific gravity than other components. 2 O 5 Ingredients: WO 3 Ingredients: Bi 2 O 3 By reducing the content of the component, the increase in specific gravity can be suppressed, leading to the miniaturization and weight reduction of optical devices. 2 O 5 +WO 3 +Bi 2 O 3 is preferably 18.0% or less, more preferably 15.0% or less, more preferably 13.0% or less, further preferably 11.0% or less, and further preferably 10.0% or less. On the other hand, from the viewpoint of increasing the refractive index and dispersion, the mass sum of Nb 2 O 5 +WO 3 +Bi 2 O 3 may be 1.0% or more. Therefore, the mass sum of Nb 2 O 5 +WO 3+Bi 2 O 3 may be preferably 1.0% or more, 2.0% or more, 3.0% or more, 4.0% or more, 5.0% or more, or 6.0% or more.

[0058] A highly stable glass can be obtained by setting the mass ratio BaO / RO, which is the ratio of the BaO component to the RO component, to 0.30 or more and 0.95 or less. In particular, in the present invention, the BaO component is the component that most enhances stability among the RO components. In addition, it can prevent the glass from cracking or chipping and the deterioration of surface accuracy during processing such as polishing. Therefore, the lower limit of the mass ratio BaO / RO is preferably 0.30 or more, more preferably 0.40 or more, even more preferably 0.50 or more, and even more preferably 0.55 or more. On the other hand, the upper limit of the mass ratio BaO / RO is preferably 0.95 or less, more preferably 0.93 or less, and even more preferably 0.90 or less.

[0059] TiO 2 Nb for components 2 O 5 Mass ratio Nb, which is the ratio of components 2 O 5 / TiO 2 By setting the mass ratio Nb to 0.50 or less, the refractive index can be increased while the specific gravity can be reduced. 2 O 5 / TiO 2 is preferably 0.50 or less, more preferably 0.48 or less, even more preferably 0.45 or less, even more preferably 0.42 or less, and most preferably 0.40 or less. 2 In order to suppress devitrification caused by niobium and to obtain a highly stable glass, the mass ratio of niobium 2 O 5 / TiO 2 may be 0.05 or more. Therefore, the mass ratio Nb 2 O 5 / TiO 2 The lower limit of is preferably 0.05 or more, more preferably 0.08 or more, even more preferably 0.10 or more, and most preferably 0.13 or more.

[0060] TiO 2Ingredients and Nb 2 O 5 ZrO relative to the total content of the components 2 Mass ratio of the components: ZrO 2 / (TiO 2 +Nb 2 O 5 ) is effective in improving resistance to devitrification by keeping it to 0.25 or less. 2 Ingredients and Nb 2 O 5 ZrO 2 If the content of the component is too high, it can cause devitrification. Mass ratio ZrO 2 / (TiO 2 +Nb 2 O 5 ) is preferably 0.25 or less, more preferably 0.20 or less, and even more preferably 0.19 or less.

[0061] TiO 2 Component, Nb 2 O 5 Ingredients: WO 3 Nb relative to the total content of the components 2 O 5 Ingredients and WO 3 The mass ratio, which is the ratio of the total content of the components (Nb 2 O 5 +WO 3 ) / (TiO 2 +Nb 2 O 5 +WO 3 ) is Nb 2 O 5 and WO 3 In order to suppress the increase in specific gravity due to the above, it is preferable to set the mass ratio (Nb 2 O 5 +WO 3 ) / (TiO 2 +Nb 2 O 5 +WO 3 ) is preferably 0.50 or less, more preferably 0.40 or less, even more preferably 0.30 or less, and even more preferably 0.28 or less. On the other hand, from the viewpoint of increasing the refractive index and dispersion, the mass ratio (Nb 2 O 5 +WO 3) / (TiO 2 +Nb 2 O 5 +WO 3 ) may be 0.05 or more. 2 O 5 +WO 3 ) / (TiO 2 +Nb 2 O 5 +WO 3 ) may have a lower limit of preferably 0.05 or more, more preferably 0.07 or more, even more preferably 0.08 or more, and even more preferably 0.10 or more.

[0062] <Ingredients that should not be included> Next, components that should not be contained in the optical glass of the present invention and components that are undesirable to be contained therein will be described. The ingredients will be explained.

[0063] Other components may be added as necessary to the extent that they do not impair the properties of the glass of the present invention. However, transition metal components such as Nd, V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, have the property of coloring the glass and absorbing specific wavelengths in the visible range even when contained alone or in combination in small amounts, so that it is preferable that they are substantially free of such components, particularly in optical glasses that use wavelengths in the visible range.

[0064] 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.

[0065] 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.

[0066] [Physical Properties] The refractive index (n d ) is preferably 1.80500 or more, 1.81000 or more, 1.82000 or more, 1.83000 or more, 1.84000 or more, 1.85000 or more, 1.86000 or more, 1.87000 or more, 1.88000 or more, 1.89000 or more, and 1.90000 or more, in that order. On the other hand, this refractive index (n d The Abbe number (ν) of the present invention may be 2.00000 or less, 1.99000 or less, 1.98000 or less, 1.97000 or less, or 1.96000 or less. d ) is preferably 17.00 or more, 18.00 or more, 19.00 or more, 20.00 or more, and 21.00 or more, in that order. d ) is preferably 30.00 or less, 28.00 or less, 27.00 or less, and 26.00 or less, in that order.

[0067] The specific gravity (d) of the optical glass of the present invention is preferably 4.43 or less, 4.30 or less, 4.20 or less, 4.10 or less, and 4.05 or less, in that order. In addition to the above, the specific gravity (d) of the optical glass of the present invention is d ) for d≦6.17×n d It is preferable to satisfy the relationship of -7.694. In producing glass, the component that increases the refractive index has a large specific gravity in addition to other components, so the specific gravity tends to increase as the content of the component that increases the refractive index increases and the refractive index increases. d By satisfying the relationship of -7.694, it was found that the specific gravity is small relative to the refractive index, which is useful in optical design. d ) preferably d≦6.17×n d The relationship of -7.694 is preferably satisfied, and more preferably d≦6.17×n d -7.800, and more preferably d≦6.17×n d The equation is to satisfy -7.914. As shown in FIG. 1, when compared with Y≧0.175X+1.137 described in Patent Document 4, d≦6.17×n dIt is clear that satisfying the relationship of -7.694 is an equation that represents a glass with a lower specific gravity relative to the refractive index.

[0068] [Manufacturing method] The optical glass of the present invention is produced, for example, as follows: the above-mentioned raw materials are mixed uniformly 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 1500°C for 2 to 5 hours depending on the melting difficulty of the glass raw materials, stirred and homogenized, and then cooled to an appropriate temperature, poured into a mold, and slowly cooled.

[0069] [Glass molding] The glass of the present invention can be melt-molded by a known method. However, the means for shaping the glass melt is not limited.

[0070] [Optical elements] A glass molded body can be produced from the produced optical glass by, for example, polishing means or mold press molding means such as reheat press molding or precision press molding. That is, a glass molded body can be produced by subjecting the optical glass to mechanical processing such as grinding and polishing. The means for producing the glass molded body are not limited to these means.

[0071] Thus, the optical glass of the present invention is useful for various optical elements and optical designs. Among them, it is particularly preferable to manufacture optical elements such as lenses and prisms. This not only reduces the weight of the optical elements, but also realizes high-definition and high-precision imaging and projection characteristics when used in optical instruments such as cameras and projectors. EXAMPLES

[0072] The compositions of the examples and comparative examples of the glass of the present invention and the refractive index (n d ), Abbe number (ν d ), specific gravity (d), and 6.17×n d -7.694, 6.17×n d -7.800, 6.17×nd The value of -7.914 is shown in Tables 1 and 2. Comparative Example B is Example 13 of WO2018 / 235725.

[0073] The glasses of the examples and comparative examples of the present invention were all produced by selecting high-purity raw materials for each component that are used in ordinary optical glass, such as the corresponding oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphate compounds, weighing them out to give the composition ratios of each example shown in the table, mixing them uniformly, and then placing them in a platinum crucible. Depending on the degree of difficulty of melting the glass raw materials, the mixture was melted in an electric furnace at a temperature range of 1100 to 1400°C for 2 to 5 hours, and then stirring and homogenizing the mixture, followed by pouring it into a mold or the like and slowly cooling it.

[0074] 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.

[0075] The specific gravity of the glass in the examples was measured based on the method for measuring density and specific gravity by the submerged weighing method of JIS Z8807:2012.

[0076] [Table 1]

[0077] [Table 2]

[0078] As shown in the table, the glasses of the examples of the present invention all have a refractive index (n d ) is 1.80500 or more, more specifically 1.85000 or more, and the refractive index (n d ) was less than or equal to 2.00000, more specifically less than or equal to 1.97000, which was within the desired range.

[0079] The glasses in the examples of the present invention all have an Abbe number (ν d ) is 17.00 or more, more specifically 21.00 or more, and this Abbe number (ν d ) was less than or equal to 30.00, more specifically less than or equal to 26.00, which was within the desired range.

[0080] The glasses of the examples of the present invention were all highly stable glasses that did not suffer from devitrification. 2 Comparative Example A, where / RO exceeded 1.50, was devitrified and did not vitrify.

[0081] The glasses of the examples of the present invention all have a value of d≦6.17×n d The relationship of -7.694, more specifically, d≦6.17×n d On the other hand, the glasses of Examples 11, 13, 19, and 22 of JP 2006-219365 A as shown in FIG. 1 and the glass of Comparative Example B as shown in FIG. 2 had a d≦6.17×n d The relationship of -7.694 was not satisfied, and the product was inferior in terms of reducing weight.

[0082] Therefore, it was clear that the optical glass of the embodiment of the present invention is a highly stable glass, while having a low specific gravity relative to its refractive index.

[0083] 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, Ln 2 O 3 The sum of the contents of the components is 10.0% or less (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb), ZrO2 content is 7.0% or less, The sum of the contents of RO components is 23.0% or more (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba); Mass ratio TiO 2 / RO is 0.5 or more and 1.5 or less, Quality and Nb 2 O 5 +WO 3 +Bi 2 O 3 が3.0% or more and 18.0% or less, Mass ratio BaO / RO is 0.30 or more and 0.95 or less and Specific gravity is d and refractive index is n ｄ When d≦6.17×n ｄ Optical glass that satisfies the relationship of -7.

694.

2. In mass% based on oxide, Nb 2 O 5 Ingredients 0-18.0%, WO 3 Ingredients 0-15.0%, La 2 O 3 Ingredients 0~10.0% 2. The optical glass according to claim 1,

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

Images