Optical glass, preforms and optical elements

Abstract

To provide an optical glass that allows a temperature coefficient of a relative refractive index to take a value of 0 or more and can contribute to compensating for the effects of temperature changes on image-forming properties, and a preform and an optical element including the same.SOLUTION: An optical glass contains, on an oxide basis in mass%, a P2O5 component of 55.0-85.0%, an Al2O3 component of 3.0-30.0%, and a ZnO component of 6.0% or more and has a temperature coefficient (40-60°C) of a relative refractive index (589.29 nm) of 0×10-6 or more.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 recent years, devices that use optical systems have rapidly become more digitalized and have higher definition. In the field of various optical devices, such as photographing devices such as digital cameras and video cameras, and image reproduction (projection) devices such as projectors and projection televisions, there is a growing demand to reduce the number of optical elements, such as lenses and prisms, used in the optical system, and to make the entire optical system lighter and more compact.

[0003] On the other hand, optical elements incorporated in on-board optical devices such as on-board cameras and optical elements incorporated in optical devices that generate a lot of heat such as projectors, copy machines, laser printers, and broadcasting equipment are increasingly being used in higher temperature environments. In such high-temperature environments, the temperature of optical elements constituting the optical system is likely to fluctuate significantly during use, and in many cases the temperature reaches 100° C. or higher. In such cases, the adverse effect of temperature fluctuations on the imaging characteristics of the optical system becomes significant to a degree that cannot be ignored, so there is a demand for configuring an optical system whose imaging characteristics are less likely to be affected by temperature fluctuations.

[0004] In constructing an optical system that is less susceptible to the effects of temperature fluctuations on the imaging performance, etc., it is preferable to use in combination an optical element made of glass whose refractive index decreases as the temperature increases and whose temperature coefficient of the relative refractive index is negative, and an optical element made of glass whose refractive index increases as the temperature increases and whose temperature coefficient of the relative refractive index is positive, in order to correct the effects of temperature changes on the imaging performance, etc.

[0005] As glasses developed with a focus on the temperature coefficient of the relative refractive index, glass compositions such as those disclosed in Patent Documents 1 and 2 are known. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-132510 A [Patent Document 2] WO2007 / 049622 publication Summary of the Invention [Problem to be solved by the invention]

[0007] The glass described in Patent Document 1 relates to a fluorophosphate-based glass that focuses on the temperature coefficient of the relative refractive index, but the temperature coefficient of the relative refractive index is only −3.8 to −2.3, and the glass described in Patent Document 2 has a high transition point, so that it cannot be said that the press formability is good.

[0008] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an optical glass that has a temperature coefficient of relative refractive index of equal to or greater than 0, has good press moldability, and is capable of contributing to correcting the effects of temperature changes on imaging characteristics, as well as a preform and optical element that use the same. [Means for solving the problem]

[0009] In order to solve the above problems, the present inventors have conducted extensive testing and research, and as a result, have found that the mass % of the oxide is: 2 O 5 Composition: 55.0-85.0%, Al 2 O 3 The content of the ZnO component is 6.0% or more, and the temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) is 0×10 -6 It was found that an optical glass as described above could be obtained, and the present invention was completed. Specifically, the present invention provides the following:

[0010] (1) Mass percent based on oxides: P 2 O 5 Ingredients: 55.0-85.0%, Al2 O 3 Ingredients: 3.0-30.0%, ZnO content of 6.0% or more Contains The temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) is 0×10 -6 That's all about optical glass.

[0011] (2) Mass percent based on oxides: P 2 O 5 Ingredients: 55.0-85.0%, Al 2 O 3 Ingredients: 3.0-30.0%, ZnO content less than 6.0% MgO content is over 0%, Contains Mass sum Li 2 Ox5+Na 2 O+(K 2 O / 2) is greater than 4.0%, The temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) is 0×10 -6 That's all about optical glass.

[0012] (3) Mass ratio Al 2 O 3 / Rn 2 The optical glass according to (1) or (2), in which O is 0.5 or more (Rn is one or more selected from the group consisting of Li, Na, and K).

[0013] (4) Mass ratio Al 2 O 3 / (SiO 2 +B 2 O 3 +P 2 O 5 ) is greater than 0.

[0014] (5) The optical glass according to any one of (1) to (4), which has a glass transition point (Tg) of 600° C. or lower and a glass yield point (At) of 650° C. or lower.

[0015] (6) An optical element made of the optical glass according to any one of (1) to (5).

[0016] (7) A preform for polishing and / or precision press molding, which is made of the optical glass according to any one of (1) to (5). Effect of the Invention

[0017] According to the present invention, it is possible to provide an optical glass that has good press moldability and can contribute to correcting the effect of temperature changes on imaging characteristics, as well as a preform and an optical element that use the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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.

[0019] [Glass components] The optical glass of the present invention may be in the form of a first glass or a second glass. The composition range of each component constituting each of the first glass and the second glass is described below. In this specification, the content of each component is expressed in 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 in which each component contained in the glass is expressed with the total mass of the oxides produced being 100 mass%, 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 into oxides during melting.

[0020] <Essential and optional components of the first glass> P 2 O 5 The component is an essential component of the present invention as a glass-forming oxide. 2 O 5By containing 55.0% or more of the component, the glass stability can be increased while the transition temperature can be lowered. 2 O 5 The lower limit of the content of the component is preferably 55.0% or more, more preferably 58.0% or more, even more preferably 60.0% or more, and most preferably 63.0% or more. On the other hand, P 2 O 5 By keeping the content of the component at 85.0% or less, it is possible to reduce devitrification of the glass. 2 O 5 The upper limit of the content of the component is preferably 85.0% or less, more preferably 82.0% or less, even more preferably 80.0% or less, still more preferably 78.0% or less, and most preferably 75.0% or less.

[0021] Al 2 O 3 The Al component is an essential component of the present invention that increases the temperature coefficient of the relative refractive index. 2 O 3 The lower limit of the content of the component is preferably 3.0% or more, more preferably 4.0% or more, even more preferably 4.5% or more, still more preferably 5.0% or more, and most preferably 5.5% or more. On the other hand, Al 2 O 3 By keeping the content of this component at 30.0% or less, it is possible to suppress the deterioration of devitrification resistance and the rise in the transition temperature caused by excessive content. 2 O 3 The upper limit of the content of the component is preferably 30.0% or less, more preferably 25.0% or less, even more preferably 20.0% or less, and most preferably 18.0% or less.

[0022] The ZnO component is an essential component of the present invention, which can improve the temperature coefficient of the relative refractive index and the melting property, and can improve the press moldability. 2 It is effective to include O component, but Rn 2The O component is also a component that reduces the relative refractive index. By making the ZnO component content 6.0% or more, the same melting property can be obtained. Therefore, the lower limit of the ZnO component content is preferably 6.0% or more, more preferably 6.5% or more, even more preferably 7.5% or more, and most preferably 8.0% or more. On the other hand, by keeping the content of the ZnO component at 25.0% or less, it is possible to suppress an increase in dispersion and a decrease in devitrification resistance due to an excessive content. Therefore, the upper limit of the content of the ZnO component is preferably 25.0% or less, more preferably 22.0% or less, even more preferably 18.0% or less, even more preferably 15.0% or less, and most preferably 12.0% or less.

[0023] The MgO component is an optional component of the present invention that increases the temperature coefficient of the relative refractive index when the content is more than 0%. Among the RO components described below, the MgO component has the greatest effect of increasing the temperature coefficient of the relative refractive index. Therefore, the lower limit of the content of the MgO component is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 1.5% or more. On the other hand, by limiting the content of the MgO component to 10.0% or less, the deterioration of devitrification resistance due to the excessive content of the MgO component can be suppressed. Therefore, the upper limit of the content of the MgO component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, and most preferably 4.0% or less.

[0024] The CaO component is an optional component of the present invention that, when contained at more than 0%, improves the low-temperature melting property while increasing the temperature coefficient of the relative refractive index. Therefore, the lower limit of the CaO component content is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, even more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, by keeping the CaO content at 10.0% or less, increases in the refractive index and dispersion can be suppressed. Therefore, the upper limit of the CaO content is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 7.0% or less, even more preferably 4.0% or less, and most preferably 3.0% or less.

[0025] The SrO component is an optional component of the present invention that, when contained at more than 0%, improves the low-temperature melting property while increasing the temperature coefficient of the relative refractive index. Therefore, the lower limit of the content of the SrO component is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, even more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, by keeping the content of the SrO component at 10.0% or less, increases in the refractive index and dispersion can be suppressed. Therefore, the upper limit of the content of the SrO component is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 7.0% or less, still more preferably 4.0% or less, and most preferably 3.0% or less.

[0026] The BaO component is an optional component of the present invention that increases the temperature coefficient of the relative refractive index while increasing the stability of the glass when it is contained at more than 0%. Therefore, the lower limit of the content of the BaO component is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, even more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, by keeping the content of the BaO component at 15.0% or less, increases in the refractive index and dispersion can be suppressed. Therefore, the upper limit of the content of the BaO component is preferably 15.0% or less, more preferably 13.0% or less, even more preferably 11.0% or less, and most preferably 9.0% or less.

[0027] Li 2 The O component is an optional component that improves low-temperature melting properties when it is contained in an amount of more than 0%. 2 The lower limit of the O component content is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.3% or more, and most preferably 0.5% or more. On the other hand, Li 2 By keeping the O content below 10.0%, 2 This prevents glass devitrification caused by excessive O content. 2The upper limit of the O content 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, even more preferably 2.0% or less, and most preferably 1.5% or less.

[0028] Na 2 The O component is an optional component that improves low-temperature melting properties when it is contained in an amount of more than 0%. 2 The lower limit of the O component content is preferably more than 0%, more preferably 0.01% or more, more preferably 0.3% or more, even more preferably 0.5% or more, still more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, Na 2 By keeping the O content below 15.0%, Na 2 It is possible to prevent glass devitrification caused by excessive O content. 2 The upper limit of the O content is preferably 15.0% or less, more preferably 12.0% or less, even more preferably 10.0% or less, still more preferably 8.0% or less, even more preferably 7.0% or less, and most preferably 5.5% or less.

[0029] K 2 The O component is an optional component that improves low-temperature melting properties when it is contained in an amount of more than 0%. 2 The lower limit of the O component content is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, still more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, K 2 By keeping the O content below 15.0%, 2 It is possible to prevent devitrification of glass caused by excessive O content. 2 The upper limit of the O content is preferably 15.0% or less, more preferably 12.0% or less, even more preferably 10.0% or less, still more preferably 8.0% or less, still more preferably 6.0% or less, and most preferably 5.5% or less.

[0030] B 2 O 3The component is an optional component that, when present at greater than 0%, promotes stable glass formation. On the other hand, B 2 O 3 If the component is contained in excess, it will cause devitrification of the glass and a decrease in the glass transition point. 2 O 3 The upper limit of the content of the component is preferably 10.0% or less, more preferably 7.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, and most preferably 1.0% or less.

[0031] SiO 2 The component is a glass-forming oxide component that, when contained in an amount of more than 0%, can improve the viscosity of the molten glass. On the other hand, SiO 2 When contained in excess, the glass may lose its vitrification or the glass transition point may decrease. 2 Ingredient is B. 2 O 3 Therefore, SiO 2 The upper limit of the component content is preferably 10.0% or less, more preferably 7.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably 1.0% or less.

[0032] La 2 O 3 Component, Gd 2 O 3 Component, Y 2 O 3 Components and Yb 2 O 3 The component is an optional component that, when present at greater than 0%, provides a high refractive index. In particular, La 2 O 3 Component, Gd 2 O 3 Component, Y 2 O 3 Components and Yb 2 O 3 By keeping the content of each component at 15.0% or less, the decrease in Abbe number can be suppressed, devitrification can be reduced, and coloring can be reduced.2 O 3 Component, Gd 2 O 3 Component, Y 2 O 3 Components and Yb 2 O 3 The upper limit of each of the component contents is preferably 15.0% or less, more preferably 10.0% or less, even more preferably 8.0% or less, and most preferably 5.0% or less.

[0033] TiO 2 The component is an optional component that, when present at greater than 0%, can increase the refractive index of the glass. 2 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0034] Ta 2 O 5 The component is an optional component that, when present at more than 0%, can increase the refractive index of the glass. 2 O 5 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2 O 5 The content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%. 2 O 5 It may not contain any ingredients.

[0035] WO 3 The component is an optional component that, when present at more than 0%, can increase the refractive index of the glass. 3 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 3The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0036] ZrO 2 The component is an optional component that, when present at more than 0%, can increase the refractive index and dispersion of the glass. 2 If the content of this component exceeds 10.0%, it becomes difficult to achieve the desired refractive index and Abbe number. 2 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0037] Nb 2 O 5 The component is an optional component that, when present at more than 0%, can increase the refractive index and dispersion of the glass. 2 O 5 If the content of Nb exceeds 10.0%, it becomes difficult to obtain the desired refractive index and Abbe number. 2 O 5 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0038] Bi 2 O 3 The component is an optional component that, when contained in an amount of more than 0%, can increase the refractive index and lower the glass transition point. 2 O 3 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2 O 3 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0039] TeO 2The component is an optional component that, when present at more than 0%, can increase the refractive index of the glass. 2 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2 The content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%. From the viewpoint of reducing material costs, TeO 2 It may not contain any ingredients.

[0040] The F component is an optional component that, when contained in an amount of more than 0%, provides a defoaming effect while reducing dispersion. 2 O 5 Ingredients and Al 2 O 3 Since it contains a large amount of F component, bubbles tend to remain during melting. Therefore, the lower limit of the F component content is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.5% or more, and most preferably 1.0% or more. On the other hand, by setting the content of the F component to 5.0% or less, it is possible to suppress a decrease in the temperature coefficient of the relative refractive index due to the F component. Therefore, the upper limit of the content of the F component is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably 1.5% or less.

[0041] Sb 2 O 3 The component is an optional component that can degas the glass melt when its content exceeds 0%. 2 O 3 The inclusion of this component not only provides a defoaming effect, but also improves the formation of knots, which are platinum crystals eroded from the crucible. Knots, like bubbles, deteriorate the internal quality of the glass, and are therefore problematic, particularly when used in optical elements for automotive and projector applications. On the other hand, Sb 2 O 3By keeping the content of this component at 1.0% or less, it is possible to suppress the decrease in transmittance in the short wavelength region of the visible light spectrum, the solarization of the glass, and the deterioration of the internal quality. 2 O 3 The content of the component may be preferably 1.0% or less, more preferably less than 0.7%, even more preferably 0.4% or less, and most preferably 0.3% or less.

[0042] The sulfur (hereinafter, referred to as S) component is an optional component that can defoam the molten glass when the content is more than 0 ppm. The S component is preferably added, for example, by adding a sulfate component as a glass raw material. The sulfate component is, for example, lithium sulfate hydrate (Li 2 SO 4 H 2 O), sodium sulfate (Na 2 SO 4 ), potassium sulfate (K 2 SO 4 ), magnesium sulfate (MgSO 4 ), calcium sulfate hydrate (CaSO 4 1 / 2H 2 O), strontium sulfate (SrSO 4 ), zinc sulfate hydrate (ZnSO 4 7H 2 O), lanthanum sulfate hydrate (La 2 (SO 4 ) 3 9H 2 O) is one of the following. The lower limit of the content of the S component is preferably 1 ppm or more, more preferably 10 ppm or more, and even more preferably 20 ppm or more. On the other hand, by keeping the S content at 300 ppm or less, it is possible to prevent alloying and coloring that would occur if the S content were excessively high, and therefore the upper limit of the S content is preferably 300 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less.

[0043] Sb 2 O 3Although the defoaming effect can be obtained even if the Sb component and the S component are contained alone, they may be contained together. 2 O 3 The inclusion of the component and / or the component S not only provides a defoaming effect, but also improves the formation of knots, which are platinum crystals eroded from the crucible. Knots, like bubbles, deteriorate the internal quality of the glass, and are therefore problematic when used in optical elements for in-vehicle applications and projectors. Sb 2 O 3 When both S and S components are contained, Sb 2 O 3 The content of the component is preferably 0.5% or less, more preferably 0.3% or less, even more preferably 0.2% or less, and most preferably 0.1% or less. On the other hand, the content of the S component is preferably 1 ppm or more, more preferably 10 ppm or more, even more preferably 20 ppm or more as the lower limit, and preferably 300 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less as the upper limit.

[0044] Rn 2 When 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) is more than 0%, there is an effect of improving the low-temperature melting property while reducing the dispersion. 2 The lower limit of the sum of the contents of O components is preferably more than 0%, more preferably 1.0% or more, even more preferably 2.0% or more, and most preferably 2.5% or more. On the other hand, Rn 2 The sum of the contents of the O components is preferably 15.0% or less, since excessive content of the O components may deteriorate the devitrification resistance. 2 The upper limit of the sum of the contents of the O components is preferably 15.0% or less, more preferably 12.0% or less, further preferably 10.0% or less, and most preferably 9.0% or less.

[0045] 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) exceeds 0%, the low-temperature meltability can be improved. Therefore, the lower limit of the sum of the contents of RO components is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, even more preferably 1.5% or more, and most preferably 2.0% or more. On the other hand, the total content of RO components is preferably 20.0% or less in order to suppress a decrease in the stability of the glass. Therefore, the upper limit of the sum of the masses of the RO components is preferably 20.0% or less, more preferably 18.0% or less, further preferably 15.0% or less, and most preferably 12.0% or less.

[0046] Ln 2 O 3 When the sum of the contents of the components (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) exceeds 0%, it is an optional component that can obtain a high refractive index. 2 O 3 The upper limit of the sum of the component contents is preferably 10.0% or less, more preferably 7.0% or less, even more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably 1.0% or less.

[0047] Mass ratio (P 2 O 5 +MgO) / (Al 2 O 3 +ZnO) can reduce the specific gravity while increasing the temperature coefficient of the relative refractive index when the mass ratio (P 2 O 5 +MgO) / (Al 2 O 3 +ZnO) is preferably 1.00 or more, more preferably 1.50 or more, even more preferably 1.80 or more, still more preferably 2.00 or more, and most preferably 2.10 or more. On the other hand, the mass ratio (P 2 O 5 +MgO) / (Al 2 O 3+ZnO) is preferably 7.00 or less, more preferably 6.00 or less, even more preferably 5.50 or less, still more preferably 5.00 or less, and most preferably 4.50 or less.

[0048] Mass sum Ka 2 O+Na 2 By making O 10.0% or less, the temperature coefficient of the relative refractive index can be increased. Therefore, the mass sum Ka 2 O+Na 2 The upper limit of O is preferably 10.0% or less, more preferably 9.0% or less, and most preferably 8.0% or less.

[0049] Mass ratio Al 2 O 3 / Rn 2 When O is 0.5 or more, Rn after vitrification 2 It is possible to suppress the dissolution of O components and increase the temperature coefficient of the relative refractive index. 2 O 3 / Rn 2 The lower limit of O is preferably 0.5 or more, more preferably 0.7 or more, even more preferably 0.8 or more, still more preferably 0.9 or more, and most preferably 1.0 or more. On the other hand, the mass ratio of Al 2 O 3 / Rn 2 By setting O to infinity, Al 2 O 3 Therefore, the mass ratio of Al can be reduced by adding an excessive amount of Al. 2 O 3 / Rn 2 The upper limit of O is preferably infinity, more preferably 10.0 or less, more preferably 7.0 or less, even more preferably 5.0 or less, and most preferably 4.0 or less.

[0050] Mass ratio RO / (SiO 2 +B 2 O 3 +P 2 O 5 +Rn 2When the mass ratio RO / (SiO O) is within a desired range, it is possible to increase the temperature coefficient of the relative refractive index while improving the melting property. 2 +B 2 O 3 +P 2 O 5 +Rn 2 O) has a lower limit of preferably more than 0, more preferably 0.01 or more, and most preferably 0.02 or more. On the other hand, the mass ratio RO / (SiO 2 +B 2 O 3 +P 2 O 5 +Rn 2 O) is preferably 0.90 or less, more preferably 0.70 or less, even more preferably 0.50 or less, still more preferably 0.30 or less, and most preferably 0.20 or less as an upper limit.

[0051] Al 2 O 3 The component is a component that must be included to improve the temperature coefficient of the relative refractive index, and is a network-forming oxide, SiO 2 Ingredients, B 2 O 3 Ingredients, P 2 O 5 Depending on the ratio of the other components, it may affect the meltability and stability of the glass. Mass ratio Al 2 O 3 / (SiO 2 +B 2 O 3 +P 2 O 5 ) is preferably greater than 0, more preferably 0.05 or greater, even more preferably 0.08 or greater, and most preferably greater than 0.10. On the other hand, the mass ratio of Al 2 O 3 / (SiO 2 +B 2 O 3 +P 2 O 5 ) is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.5 or less, and most preferably 0.3 or less.

[0052] In the present invention, it is preferable that the total content of the following components is 98.0% or more, 99.0% or more, 99.5% or more, and 99.8% or more in that order. P 2 O 5 Ingredients: SiO 2 Ingredients, B 2 O 3 Ingredients, Al 2 O 3 component, MgO component, CaO component, SrO component, BaO component, Li 2 O component, Na 2 O component, K 2 O component, La 2 O 3 Component, Y 2 O 3 Component, Gd 2 O 3 Ingredients, Yb 2 O 3 Component, TiO 2 Component, Nb 2 O 5 Ingredients: WO 3 Ingredients: Bi 2 O 3 Component, ZnO component, ZrO 2 Ingredients, Ta 2 O 5 Component: Sb 2 O 3 component, F component.

[0053] <Required and optional components of the second glass> P 2 O 5 The component is an essential component of the present invention as a glass-forming oxide. 2 O 5 By containing 55.0% or more of the component, the glass stability can be increased while the transition point can be lowered. 2 O 5 The lower limit of the content of the component is preferably 55.0% or more, more preferably 58.0% or more, even more preferably 60.0% or more, and most preferably 63.0% or more. On the other hand, P 2 O 5By keeping the content of the component at 85.0% or less, it is possible to reduce devitrification of the glass. 2 O 5 The upper limit of the content of the component is preferably 85.0% or less, more preferably 82.0% or less, even more preferably 80.0% or less, still more preferably 78.0% or less, and most preferably 75.0% or less.

[0054] Al 2 O 3 The Al component is an essential component of the present invention that increases the temperature coefficient of the relative refractive index. 2 O 3 The lower limit of the content of the component is preferably 3.0% or more, more preferably 4.0% or more, even more preferably 4.5% or more, still more preferably 5.0% or more, and most preferably 5.5% or more. On the other hand, Al 2 O 3 By keeping the content of this component at 30.0% or less, it is possible to suppress the deterioration of devitrification resistance and the rise in the transition temperature caused by excessive content. 2 O 3 The upper limit of the content of the component is preferably 30.0% or less, more preferably 25.0% or less, even more preferably 20.0% or less, and most preferably 18.0% or less.

[0055] The MgO component is an essential component of the present invention that increases the temperature coefficient of the relative refractive index. Among the RO components described below, the MgO component has the greatest effect of increasing the temperature coefficient of the relative refractive index, and can suppress a decrease in the relative refractive index even when the content of the ZnO component is small. Therefore, the lower limit of the content of the MgO component is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 1.2% or more. On the other hand, by limiting the content of the MgO component to 10.0% or less, the deterioration of devitrification resistance due to the excessive content of the MgO component can be suppressed. Therefore, the upper limit of the content of the MgO component is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, and most preferably 6.0% or less.

[0056] The ZnO component is an optional component of the present invention that can increase the temperature coefficient of relative refractive index and melting property when contained at more than 0%. Therefore, the lower limit of the content of the ZnO component is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, even more preferably 2.0% or more, and most preferably 3.0% or more. On the other hand, by setting the content of the ZnO component to less than 6.0%, it is possible to suppress an increase in dispersion and a decrease in devitrification resistance due to an excessive content. Therefore, the upper limit of the content of the ZnO component is preferably less than 6.0%, more preferably 5.5% or less, even more preferably 5.0% or less, and most preferably 4.5% or less.

[0057] The CaO component is an optional component of the present invention that, when contained at more than 0%, improves the low-temperature melting property while increasing the temperature coefficient of the relative refractive index. Therefore, the lower limit of the CaO component content is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, even more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, by keeping the CaO content at 10.0% or less, increases in the refractive index and dispersion can be suppressed. Therefore, the upper limit of the CaO content is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 7.0% or less, even more preferably 4.0% or less, and most preferably 3.0% or less.

[0058] The SrO component is an optional component of the present invention that, when contained at more than 0%, improves the low-temperature melting property while increasing the temperature coefficient of the relative refractive index. Therefore, the lower limit of the content of the SrO component is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, even more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, by keeping the content of the SrO component at 10.0% or less, increases in the refractive index and dispersion can be suppressed. Therefore, the upper limit of the content of the SrO component is preferably 10.0% or less, more preferably 9.0% or less, even more preferably 7.0% or less, still more preferably 4.0% or less, and most preferably 2.0% or less.

[0059] The BaO component is an optional component of the present invention that increases the temperature coefficient of the relative refractive index while increasing the stability of the glass when it is contained at more than 0%. Therefore, the lower limit of the content of the BaO component is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, even more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, by keeping the content of the BaO component at 15.0% or less, increases in the refractive index and dispersion can be suppressed. Therefore, the upper limit of the content of the BaO component is preferably 15.0% or less, more preferably 13.0% or less, even more preferably 11.0% or less, and most preferably 9.0% or less.

[0060] Li 2 The O component is an optional component that improves low-temperature melting properties when it is contained in an amount of more than 0%. 2 The lower limit of the O component content is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.3% or more, and most preferably 0.5% or more. On the other hand, Li 2 By keeping the O content below 10.0%, 2 This prevents glass devitrification caused by excessive O content. 2 The upper limit of the O content 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, even more preferably 2.0% or less, and most preferably 1.5% or less.

[0061] Na 2 The O component is an optional component that improves low-temperature melting properties when it is contained in an amount of more than 0%. 2 The lower limit of the O component content is preferably more than 0%, more preferably 0.01% or more, more preferably 0.3% or more, even more preferably 0.5% or more, still more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, Na 2 By keeping the O content below 15.0%, Na 2 It is possible to prevent glass devitrification caused by excessive O content. 2The upper limit of the O content is preferably 15.0% or less, more preferably 12.0% or less, even more preferably 10.0% or less, still more preferably 8.0% or less, even more preferably 7.0% or less, and most preferably 5.5% or less.

[0062] K 2 The O component is an optional component that improves low-temperature melting properties when it is contained in an amount of more than 0%. 2 The lower limit of the O component content is preferably more than 0%, more preferably 0.3% or more, even more preferably 0.5% or more, still more preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, K 2 By keeping the O content below 15.0%, 2 It is possible to prevent devitrification of glass caused by excessive O content. 2 The upper limit of the O content is preferably 15.0% or less, more preferably 12.0% or less, even more preferably 10.0% or less, still more preferably 8.0% or less, still more preferably 6.0% or less, and most preferably 5.5% or less.

[0063] B 2 O 3 The component is an optional component that, when present at greater than 0%, promotes stable glass formation. On the other hand, B 2 O 3 If the component is contained in excess, it will cause devitrification of the glass and a decrease in the transition point. 2 O 3 The upper limit of the content of the component is preferably 10.0% or less, more preferably 7.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, and most preferably 1.0% or less.

[0064] SiO 2 The component is a glass-forming oxide component that, when contained in an amount of more than 0%, can improve the viscosity of the molten glass. On the other hand, SiO 2 If the component is contained in excess, it may cause devitrification of the glass or a decrease in the transition point. 2 Ingredient is B.2 O 3 Therefore, SiO 2 The upper limit of the component content is preferably 10.0% or less, more preferably 7.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably 1.0% or less.

[0065] La 2 O 3 Component, Gd 2 O 3 Component, Y 2 O 3 Components and Yb 2 O 3 The component is an optional component that, when present at greater than 0%, provides a high refractive index. In particular, La 2 O 3 Component, Gd 2 O 3 Component, Y 2 O 3 Components and Yb 2 O 3 By keeping the content of each component at 15.0% or less, the decrease in Abbe number can be suppressed, devitrification can be reduced, and coloring can be reduced. 2 O 3 Component, Gd 2 O 3 Component, Y 2 O 3 Components and Yb 2 O 3 The upper limit of each of the component contents is preferably 15.0% or less, more preferably 10.0% or less, even more preferably 8.0% or less, and most preferably 5.0% or less.

[0066] TiO 2 The component is an optional component that, when present at greater than 0%, can increase the refractive index of the glass. 2 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0067] Ta 2 O 5 The component is an optional component that, when present at more than 0%, can increase the refractive index of the glass. 2 O 5 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2 O 5 The content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%. 2 O 5 It may not contain any ingredients.

[0068] WO 3 The component is an optional component that, when present at more than 0%, can increase the refractive index of the glass. 3 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 3 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0069] ZrO 2 The component is an optional component that, when present at more than 0%, can increase the refractive index and dispersion of the glass. 2 If the content of this component exceeds 10.0%, it becomes difficult to achieve the desired refractive index and Abbe number. 2 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0070] Nb 2 O 5The component is an optional component that, when present at more than 0%, can increase the refractive index and dispersion of the glass. 2 O 5 If the content of Nb exceeds 10.0%, it becomes difficult to obtain the desired refractive index and Abbe number. 2 O 5 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0071] Bi 2 O 3 The component is an optional component that, when contained in an amount of more than 0%, can increase the refractive index and lower the glass transition point. 2 O 3 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2 O 3 The upper limit of the content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%.

[0072] TeO 2 The component is an optional component that, when present at more than 0%, can increase the refractive index of the glass. 2 If the content of the component exceeds 10.0%, it becomes difficult to obtain the desired refractive index. 2 The content of the component is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably less than 1.0%. From the viewpoint of reducing material costs, TeO 2 It may not contain any ingredients.

[0073] The F component is an optional component that, when contained in an amount of more than 0%, provides a defoaming effect while reducing dispersion. 2 O 5 Ingredients and Al 2 O 3Since it contains a large amount of F component, bubbles tend to remain during melting. Therefore, the lower limit of the F component content is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.5% or more, and most preferably 1.0% or more. On the other hand, by setting the content of the F component to 5.0% or less, it is possible to suppress a decrease in the temperature coefficient of the relative refractive index due to the F component. Therefore, the upper limit of the content of the F component is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably 1.5% or less.

[0074] Sb 2 O 3 The component is an optional component that can degas the glass melt when its content exceeds 0%. 2 O 3 The inclusion of this component not only provides a defoaming effect, but also improves the formation of knots, which are platinum crystals eroded from the crucible. Knots, like bubbles, deteriorate the internal quality of the glass, and are therefore problematic, particularly when used in optical elements for automotive and projector applications. On the other hand, Sb 2 O 3 By keeping the content of this component at 1.0% or less, it is possible to suppress the decrease in transmittance in the short wavelength region of the visible light spectrum, the solarization of the glass, and the deterioration of the internal quality. 2 O 3 The content of the component may be preferably 1.0% or less, more preferably less than 0.7%, even more preferably 0.4% or less, and most preferably 0.3% or less.

[0075] The sulfur (hereinafter, referred to as S) component is an optional component that can defoam the molten glass when the content is more than 0%. The S component is preferably added, for example, by adding a sulfate component as a glass raw material. The sulfate component is, for example, lithium sulfate hydrate (Li 2 SO 4 H 2 O), sodium sulfate (Na 2 SO 4 ), potassium sulfate (K 2 SO4 ), magnesium sulfate (MgSO 4 ), calcium sulfate hydrate (CaSO 4 1 / 2H 2 O), strontium sulfate (SrSO 4 ), zinc sulfate hydrate (ZnSO 4 7H 2 O), lanthanum sulfate hydrate (La 2 (SO 4 ) 3 9H 2 O) is one of the following. The lower limit of the content of the S component is preferably 1 ppm or more, more preferably 10 ppm or more, and even more preferably 20 ppm or more. On the other hand, by keeping the S content at 300 ppm or less, it is possible to prevent alloying and coloring that would occur if the S content were excessively high, and therefore the upper limit of the S content is preferably 300 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less.

[0076] Sb 2 O 3 Although the defoaming effect can be obtained even if the Sb component and the S component are contained alone, they may be contained together. 2 O 3 The inclusion of the component and / or the component S not only provides a defoaming effect, but also improves the formation of knots, which are platinum crystals eroded from the crucible. Knots, like bubbles, deteriorate the internal quality of the glass, and are therefore problematic when used in optical elements for in-vehicle applications and projectors. Sb 2 O 3 When both S and S components are contained, Sb 2 O 3 The content of the component is preferably 0.5% or less, more preferably 0.3% or less, even more preferably 0.2% or less, and most preferably 0.1% or less. On the other hand, the content of the S component is preferably 1 ppm or more, more preferably 10 ppm or more, even more preferably 20 ppm or more as the lower limit, and preferably 300 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less as the upper limit.

[0077] Rn 2 When 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) is more than 0%, there is an effect of improving the low-temperature melting property while reducing the dispersion. 2 The lower limit of the sum of the contents of O components is preferably more than 0%, more preferably 1.0% or more, even more preferably 2.0% or more, and most preferably 2.5% or more. On the other hand, Rn 2 The sum of the contents of the O components is preferably 15.0% or less, since excessive content of the O components may deteriorate the devitrification resistance. 2 The upper limit of the sum of the contents of the O components is preferably 15.0% or less, more preferably 12.0% or less, further preferably 10.0% or less, and most preferably 8.0% or less.

[0078] 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) exceeds 0%, the low-temperature meltability can be improved. Therefore, the lower limit of the sum of the contents of RO components is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, even more preferably 1.5% or more, and most preferably 2.0% or more. On the other hand, the total content of RO components is preferably 20.0% or less in order to suppress a decrease in the stability of the glass. Therefore, the upper limit of the sum of the masses of the RO components is preferably 20.0% or less, more preferably 18.0% or less, further preferably 15.0% or less, and most preferably 12.0% or less.

[0079] Ln 2 O 3 When the sum of the contents of the components (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) exceeds 0%, it is an optional component that can obtain a high refractive index. 2 O 3The upper limit of the sum of the component contents is preferably 10.0% or less, more preferably 7.0% or less, even more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.0% or less, and most preferably 1.0% or less.

[0080] In the present invention, Li 2 The value obtained by multiplying the O content by 5 and Na 2 The content of O and Ka 2 The mass sum of Li with the content of O component halved 2 Ox5+Na 2 O+(K 2 By making the mass sum of LiO / 2 exceed 4.0%, the glass transition temperature can be lowered. 2 Ox5+Na 2 O+(K 2 The lower limit of O / 2) is preferably more than 4.0%, more preferably 4.5% or more, even more preferably 5.0% or more, and most preferably 5.5% or more.

[0081] Mass ratio (P 2 O 5 +MgO) / (Al 2 O 3 +ZnO) can reduce the specific gravity while increasing the temperature coefficient of the relative refractive index when the mass ratio (P 2 O 5 +MgO) / (Al 2 O 3 +ZnO) is preferably 1.00 or more, more preferably 1.50 or more, even more preferably 1.80 or more, still more preferably 2.00 or more, and most preferably 3.00 or more. On the other hand, the mass ratio (P 2 O 5 +MgO) / (Al 2 O 3 +ZnO) is preferably 10.00 or less, more preferably 9.00 or less, even more preferably 8.00 or less, still more preferably 7.50 or less, and most preferably 7.00 or less as the upper limit.

[0082] Mass sum Ka 2 O+Na 2By making O 10.0% or less, the temperature coefficient of the relative refractive index can be increased. Therefore, the mass sum Ka 2 O+Na 2 The upper limit of O is preferably 10.0% or less, more preferably 9.0% or less, and most preferably 8.0% or less.

[0083] Mass ratio Al 2 O 3 / Rn 2 When O is 0.5 or more, Rn after vitrification 2 It is possible to suppress the dissolution of O components and increase the temperature coefficient of the relative refractive index. 2 O 3 / Rn 2 The lower limit of O is preferably 0.5 or more, more preferably 0.7 or more, even more preferably 1.0 or more, still more preferably 1.2 or more, and most preferably 1.5 or more. On the other hand, the mass ratio of Al 2 O 3 / Rn 2 By setting O to infinity, Al 2 O 3 Therefore, the mass ratio of Al can be reduced by adding an excessive amount of Al. 2 O 3 / Rn 2 The upper limit of O is preferably infinity, more preferably 8.0 or less, more preferably 6.0 or less, even more preferably 4.0 or less, and most preferably 3.0 or less.

[0084] Mass ratio RO / (SiO 2 +B 2 O 3 +P 2 O 5 +Rn 2 When the mass ratio RO / (SiO O) is within a desired range, it is possible to increase the temperature coefficient of the relative refractive index while improving the melting property. 2 +B 2 O 3 +P 2 O 5 +Rn 2 O) has a lower limit of preferably more than 0, more preferably 0.01 or more, and most preferably 0.02 or more. On the other hand, the mass ratio RO / (SiO 2 +B 2 O 3 +P 2 O 5 +Rn 2 O) is preferably 0.90 or less, more preferably 0.70 or less, even more preferably 0.50 or less, still more preferably 0.30 or less, and most preferably 0.20 or less as the upper limit.

[0085] Al 2 O 3 The component is a component that must be included to improve the temperature coefficient of the relative refractive index, and is a network-forming oxide, SiO 2 Ingredients, B 2 O 3 Ingredients, P 2 O 5 Depending on the ratio of the other components, it may affect the meltability and stability of the glass. Mass ratio Al 2 O 3 / (SiO 2 +B 2 O 3 +P 2 O 5 ) is preferably more than 0, more preferably 0.05 or more, even more preferably 0.10 or more, and most preferably 0.12 or more. On the other hand, the mass ratio of Al 2 O 3 / (SiO 2 +B 2 O 3 +P 2 O 5 ) is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.5 or less, and most preferably 0.3 or less.

[0086] In the present invention, it is preferable that the total content of the following components is 98.0% or more, 99.0% or more, 99.5% or more, and 99.8% or more in that order. P 2 O 5 Ingredients: SiO 2 Ingredients, B 2 O 3 Ingredients, Al2 O 3 component, MgO component, CaO component, SrO component, BaO component, Li 2 O component, Na 2 O component, K 2 O component, La 2 O 3 Component, Y 2 O 3 Component, Gd 2 O 3 Ingredients, Yb 2 O 3 Component, TiO 2 Component, Nb 2 O 5 Ingredients: WO 3 Ingredients: Bi 2 O 3 Component, ZnO component, ZrO 2 Ingredients, Ta 2 O 5 Component: Sb 2 O 3 component, F component.

[0087] <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.

[0088] 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 Cu, Nd, Er, Cs, V, Cr, Mn, Fe, Co, Ni, Ag, and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, have the property that even when contained alone or in combination in small amounts, the glass is colored and absorbs at specific wavelengths in the visible range, so it is preferable that they are not substantially contained in optical glasses that use wavelengths in the visible range, particularly.

[0089] In this specification, "substantially free" preferably means that the content is less than 0.1%, and more preferably means that the content is free except for unavoidable impurities. Here, the content of components contained as unavoidable impurities is, for example, less than 0.01% or less than 0.001%, but is not limited thereto.

[0090] In addition, lead compounds such as PbO and As 2 O 3 Arsenic compounds such as those mentioned above are components that have a high environmental impact, and therefore it is desirable to avoid their inclusion at all except in the case of unavoidable contamination.

[0091] 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.

[0092] <Physical Properties> The physical properties of the optical glass of the present invention will now be described. The optical glass of the present invention preferably has a low refractive index and a high Abbe number (low dispersion). In particular, the refractive index (n d The lower limit of the refractive index (n d ) is preferably 1.56000 or less, more preferably 1.55000 or less, and even more preferably 1.54000 or less as an upper limit. In addition, the Abbe number (ν d ) is preferably 60.00 or more, more preferably 62.00 or more, even more preferably 63.00 or more, and most preferably 64.00 or more. d ) is preferably 75.00 or less, preferably 73.00 or less, more preferably 72.00 or less, and even more preferably 71.00 or less. The optical glass of the present invention having such a refractive index and Abbe number is useful in optical design, and in particular allows the optical system to be made compact while achieving high imaging characteristics, thereby expanding the freedom of optical design.

[0093] The optical glass of the present invention has a temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) of 0×10-6 In particular, the temperature coefficient (40 to 60° C.) of the relative refractive index (589.29 nm) of the optical glass of the present invention is preferably 0×10 -6 More preferably, 0.5×10 -6 More preferably, 1.0×10 -6 The above is the lower limit. The upper limit of the temperature coefficient (40 to 60° C.) of the relative refractive index (589.29 nm) of the optical glass of the present invention is not particularly specified, but is preferably 10.0×10 -6 Less than or equal to 7.0×10 -6 Less than 5.0×10, more preferably -6 Less than 4.5×10, more preferably -6 The following may also be used. The optical glass of the present invention, which has such a temperature coefficient (40 to 60°C) of relative refractive index (589.29 nm), can be used to configure an optical system whose imaging characteristics are unlikely to be affected by temperature fluctuations, and can therefore be suitably used as an optical element for in-vehicle applications or projectors. In the present invention, the temperature coefficient (40 to 60° C.) of the relative refractive index (589.29 nm) is sometimes referred to as the relative refractive index.

[0094] The optical glass of the present invention preferably has a glass transition point (Tg) of not more than 600° C. In particular, the upper limit of the glass transition point (Tg) of the optical glass of the present invention is preferably not more than 600° C., more preferably not more than 580° C., even more preferably not more than 550° C., and most preferably not more than 520° C. The optical glass of the present invention having such a glass transition point (Tg) has excellent melting properties, and therefore devitrification during pressing can be suppressed.

[0095] The optical glass of the present invention preferably has a glass yield point (At) of 650° C. or less. In particular, the upper limit of the glass yield point (At) of the optical glass of the present invention is preferably 650° C. or less, more preferably 620° C. or less, even more preferably 600° C. or less, and most preferably 590° C. or less. The optical glass of the present invention having such a glass strain point (At) is excellent in meltability, and thus can suppress devitrification during pressing.

[0096] The optical glass of the present invention preferably has a small specific gravity. In particular, the specific gravity of the optical glass of the present invention preferably has an upper limit of 3.50 or less, more preferably 3.30 or less, still more preferably 3.10 or less, and most preferably 3.00 or less. Such an optical glass with a low specific gravity is useful in optical design. In particular, since the size of the optical system can be reduced, the degree of freedom in optical design can be expanded.

[0097] [Manufacturing method] The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a platinum crucible and produced according to a known glass manufacturing method according to the melting difficulty and melting scale of the glass raw materials.

[0098] [Glass forming] The glass of the present invention can be melt-formed by a known method. Note that the means for forming the glass melt is not limited.

[0099] [Preform and optical element] From the produced optical glass, a glass formed body can be produced using, for example, means such as polishing, or means of mold pressing such as reheat pressing or precision pressing. That is, a glass formed body is produced by performing machining such as grinding and polishing on the optical glass, or a preform for mold pressing is produced from the optical glass, and after performing reheat pressing on this preform, polishing is performed to produce a glass formed body, or a preform produced by polishing or a preform formed by known floating forming or the like is precision pressed to produce a glass formed body. Note that the means for producing the glass formed body is not limited to these means.

Examples

[0100] The compositions of the examples and comparative examples of the glass of the present invention, the refractive indexes of these glasses (n d ), Abbe number (ν d ), temperature coefficient (40 to 60°C) of relative refractive index (589.29 nm), transition point (Tg), yield point (At), and specific gravity are shown in Tables 1 to 4. Examples 1 to 7 are the first glass component, Examples 8 to 15 are the second glass component, Comparative Example A is Example 44 of WO2018 / 211861, and Comparative Example B is Example 12 of WO2007 / 049622. Note that the following examples are merely for illustrative purposes, and the present invention is not limited to these examples.

[0101] For the glasses of the examples of the glass 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, weighed out to obtain the composition ratio of each example shown in the table, and mixed uniformly. 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.

[0102] The refractive index (n d ) is measured using the V-block method specified in JIS B 7071-2:2018 for the d-line (587.56 nm) of a helium lamp. The Abbe number (ν d ) is the refractive index of the d line and the refractive index of the F line (486.13 nm) of a hydrogen lamp (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 )] was calculated using the formula:

[0103] The relative refractive index of the glasses in the examples was measured by measuring the temperature coefficient of the relative refractive index at 40 to 60° C. for light with a wavelength of 589.29 nm in accordance with the interference method defined in JIS B 7072-2:2020.

[0104] The glass transition point (Tg) and yield point (At) of the glasses in the examples were determined from a thermal expansion curve obtained by measuring the relationship between temperature and elongation of a sample in accordance with the Japan Optical Glass Industry Association standard JOGIS08-2019 "Method for measuring thermal expansion of optical glass."

[0105] 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.

[0106] [Table 1]

[0107] [Table 2]

[0108] [Table 3]

[0109] [Table 4]

[0110] The optical glasses according to the embodiments of the present invention all have a temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) of 0×10 -6 That was all.

[0111] Moreover, the optical glasses of the Examples all had a glass transition point (Tg) of 600° C. or lower and a glass yield point (At) of 650° C. or lower.

[0112] Moreover, the optical glasses of the examples all had a specific gravity of 3.5 or less.

[0113] Furthermore, the optical glasses of the Examples formed stable glasses, and devitrification was unlikely to occur during the glass production.

[0114] Therefore, the optical glass of the embodiment has a temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) of 0×10 -6 The optical glass had few bubbles and a low specific gravity. From this, it is presumed that the optical glass of the embodiment of the present invention has a high temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) and good internal quality, and therefore can be suitably used for in-vehicle cameras and projectors.

[0115] 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.

[0116] 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, P 2 O 5 Ingredients: 55.0-85.0%, A 2 O 3 Ingredients: 5.5 to 30.0%, MgO content is over 0% Contains The ZnO content is less than 6.0%. B 2 O 3 The component is 1.0% or less, The TiO 2 component is less than 1.0%. Rn 2 The sum of the contents of O components is 10.0% or less (wherein Rn is one or more selected from the group consisting of Li, Na, and K); Mass sum Li 2 Ox5 + Na 2 O+(K 2 O / 2) is greater than 4.0%, the sum of the contents of Ln 2 O 3 components is 1.0% or less (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb); containing a P2O5 component, a SiO2 component, a B2O3 component, an Al2O3 component, an MgO component, a CaO component, a SrO component, a BaO component, a Li2O component, a Na2O component, a K2O component, a La2O3 component, a Y2O3 component, a Gd2O3 component, a Yb2O3 component, a TiO2 component, a Nb2O5 component, a WO3 component, a Bi2O3 component, a ZnO component, a ZrO2 component, a Ta2O5 component, a Sb2O3 component, and an F component in a total amount of 99.8% or more, Contains no Cu, Nd, or Fe components except for unavoidable impurities; The temperature coefficient (40 to 60°C) of the relative refractive index (589.29 nm) is 0x10 -6 That's all about optical glass.

2. Mass ratio Al 2 O 3 / Rn 2 2. The optical glass according to claim 1, wherein O is 0.7 or more (wherein Rn is one or more selected from the group consisting of Li, Na, and K).

3. Mass ratio Al 2 O 3 / (SiO 2 +B 2 O 3 +P 2 O 5 3. The optical glass according to claim 1, wherein the refractive index is 0.10 or more.

4. 4. The optical glass according to claim 1, which has a glass transition point (Tg) of 600° C. or lower and a glass yield point (At) of 650° C. or lower.

5. An optical element comprising the optical glass according to any one of claims 1 to 4.

6. A preform for polishing and / or precision press molding, which is made of the optical glass according to any one of claims 1 to 4.

Images