Optical glass and optical element

Abstract

To provide an optical glass with excellent formability, high stability during the production process, and excellent color correction over a broad range, as well as an optical element including the optical glass.SOLUTION: An optical glass according to the present invention is characterized in that: the refractive index (nd) at the helium d-line wavelength (587.6 nm) is in the range of 1.45000 to 1.65000; the ISO color characteristic index (ISO / CCI) is 0.00 for blue (B), 0.80 or less for green (G), and 0.80 or less for red (R); and the value of S, derived from the equation S=E α / (1-ν), is within the range of 0.70×106 or more and less than 1.03×106 (Pa / °C), where E denotes Young's modulus (unit: GPa), α denotes the average linear expansion coefficient in the temperature range of 100°C to 300°C (unit: 10-7°C-1), and ν denotes Poisson's ratio.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to optical glass and optical elements, and in particular to optical glass having a refractive index that is in a range relatively lower than conventional ones and a color characteristic index with a small degree of color change, which optical glass has excellent moldability, high stability in the manufacturing process, and excellent color correction over a wide range, and to optical elements using said optical glass. [Background technology]

[0002] When manufacturing optical elements, optical glass is used as the raw material, and conventional methods for producing optical elements from optical glass include, for example, a method in which a gob or glass block formed from optical glass is ground or polished to obtain the shape of an optical element (e.g., JP 2001-166117 A), a method in which a gob or glass block formed from optical glass is reheated and molded (reheat press molding) to obtain a glass molded body (e.g., JP 2001-19446 A), and a method in which a preform material obtained from a gob or glass block is molded in an ultra-precisely machined mold (precision mold press molding) to obtain the shape of an optical element (e.g., JP 2005-281106 A).

[0003] In addition, a recent method for producing optical elements includes stacking glass plates made of optical glass, polishing and coating them, and then cutting, cleaning, polishing, forming, and other steps to produce optical elements.

[0004] However, when there are many steps involved in manufacturing an optical element from optical glass, the inherent properties of the optical glass change, resulting in problems in that the physical properties of the optical element are affected. In particular, the cutting and forming steps have a large effect on the physical properties of the optical element, and are prone to cracking and chipping. For these reasons, optical glass that is excellent in formability and highly stable during the manufacturing process is required.

[0005] Recently, optical elements are increasingly being used in wearable applications such as AR (Augmented Reality), VR (Virtual Reality), and MR (Mixed Reality) as well as in mobile devices. Examples include wearable applications such as glasses with projectors, eyeglass-type and goggle-type displays, virtual reality and augmented reality display devices, and virtual image display devices, as well as mobile device applications such as mobile phones and smartphones.

[0006] The following, for example, discloses inventions of optical glass for wearable applications. JP 2019-511449 A discloses an invention of a high-refractive-index optical glass having a refractive index of more than 1.65 at a wavelength λ=587.6 nm as an optical glass that can be used in virtual or augmented reality devices. JP 2021-102549 A discloses an invention of an optical glass having a refractive index nd of 1.95 or more, containing at least one selected from TiO2 and Nb2O5 as well as B2O3 as a glass composition. Furthermore, JP 2021-31378 A discloses an invention for a high refractive index optical glass containing, expressed in mole percentages based on oxides, 9.0-11.0% SiO2, 22.0-24.0% B2O3, 18.0-20.0% La2O3, and 30.0-31.0% TiO2, and having a refractive index in the range of 1.90 to 2.10.

[0007] All of these inventions are inventions of optical glass having a high refractive index, which was made from the viewpoint that a high refractive index is required for optical glass for wearable applications. However, in order to increase the refractive index, it is necessary to contain a high proportion of components that significantly increase the refractive index of the glass, such as TiO2 and Nb2O5. If such components that significantly increase the refractive index of the glass are contained in the glass in a high proportion, the vitrification becomes unstable, so it becomes necessary to contain a high proportion of B2O3 in the glass to stabilize the vitrification. For example, in the above-mentioned JP 2021-31378 A, an optical glass having a high refractive index in the range of 1.90 to 2.10 is obtained by containing 30.0 to 31.0% TiO2 and further containing 22.0 to 24.0% B2O3 in mole percent on an oxide basis.

[0008] However, depending on the configuration and design freedom of the optical elements used in wearable devices or mobile devices, a high refractive index is not necessarily required. And the optical glass used to manufacture optical elements that do not require a high refractive index does not necessarily have to have a high refractive index, and if the optical glass does not necessarily have to have a high refractive index, there is no need to contain a high proportion of components that significantly increase the refractive index of the glass, such as TiO2 or Nb2O5, in the glass, and as a result, there is no need to contain a high proportion of B2O3 in the glass to stabilize the vitrification.

[0009] For optical glass used in the manufacture of wearable devices and mobile devices, which does not necessarily require a high refractive index, what is required is a color characteristic index that exhibits a low degree of color change and excellent color correction over a wide range, rather than the refractive index itself. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2001-166117 A [Patent Document 2] JP 2001-19446 A [Patent Document 3] JP 2005-281106 A [Patent Document 4] Special Publication No. 2019-511449 [Patent Document 5] JP 2021-102549 A [Patent Document 6] Patent Publication No. 2021-31378 [Patent Document 7] Patent No. 4537317 specification Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above problems, and its object is to provide a method for determining the refractive index (n d The present invention provides an optical glass having a color characteristic index with a relatively lower range than conventional ones and a small degree of color change, which has excellent moldability, high stability in the manufacturing process, and excellent color correction over a wide range, and an optical element using said optical glass. [Means for solving the problem]

[0012] In order to solve the above problems, the optical glass according to the present invention has a refractive index (n d ) is in the range of 1.45000 to 1.65000, the ISO color characteristic index ISO / CCI is in the range of 0.00 for blue (B), 0.80 or less for green (G), and 0.80 or less for red (R), and the value of S calculated by the following formula (1) is 0.70×10 6 More than 1.03 x 10 6 In formula (1), E is Young's modulus (unit: GPa), α is the average linear expansion coefficient (unit: 10 -7 ℃ -1 ), and ν is Poisson's ratio. S = E α / (1 - ν) Equation (1)

[0013] Preferably, the refractive index (n d ) has an upper limit of 1.64000.

[0014] Also, preferably, the ISO color characteristic index ISO / CCI is in the range of 0.00 for blue (B), 0.70 or less for green (G), and 0.70 or less for red (R).

[0015] Also, preferably, the value of S is 0.73×10 6 Above 1.00 x 10 6 (Pa / ℃).

[0016] In one embodiment, the total content of the TiO2 component, the Nb2O5 component, the Bi2O3 component, and the WO3 component is 10.0% or less in mole percent based on the oxides.

[0017] In one embodiment, the composition contains, in mole percent based on oxides, 30.0 to 80.0% of SiO2 component and 0.00 to 30.0% of B2O3 component, with the proviso that the sum of the SiO2 component and the B2O3 component does not exceed 100.0%.

[0018] The optical element according to the present invention is an optical element made of the above optical glass.

[0019] In one embodiment, such an optical element is used together with a transparent resin plate or a curable resin material.

[0020] In one embodiment, such an optical element is used in a wearable device or a mobile device. Effect of the Invention

[0021] According to the present invention, the refractive index (n dThe present invention provides an optical glass having a color characteristic index with a relatively low range compared to conventional ones and a low degree of color change, which has excellent moldability, high stability in the manufacturing process, and excellent color correction over a wide range. Such an optical glass is suitable for wearable applications such as AR (augmented reality), VR (virtual reality), and MR (mixed reality), as well as for mobile device applications. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The optical glass according to the present invention and the optical element using the same will be described in detail below.

[0023] [A: Optical glass of the present invention] 1. Color characteristic index (ISO / CCI) As described above, the optical glass according to the present invention is an optical glass having a color characteristic index with a low degree of color change. Specifically, when the color characteristics are expressed by the ISO color characteristic index (ISO / CCI) specified by the Japanese Industrial Standards, the ISO color characteristic index ISO / CCI when converted into a flat plate with a thickness of 10 mm is in the range of 0.00 for blue (B), 0.80 or less for green (G), and 0.80 or less for red (R).

[0024] The Color Condition Index (CCI) is an index used to predict the degree to which the color of a color photograph taken using a certain lens system will change compared to the original color due to the spectral characteristics of the lens, and is a set of three values ​​determined for each color: blue (B), green (G), and red (R). This ISO / CCI makes it possible to predict the degree to which color will change for a single glass material. For measurements and calculations, JIS B 7097 can be used as a reference.

[0025] In general, the ISO / CCI of optical glass indicates that the better the light transmittance of a glass in the short wavelength region of visible light, the smaller the G and R values ​​will be when the ISO / CCI B value is set to 0. However, when attempting to obtain optical glass with a high refractive index, the devitrification resistance and melting properties decrease. Furthermore, if the melting temperature is increased or the melting time is extended in order to improve the devitrification resistance and melting properties, there is the disadvantage that the ISO / CCI G and R values ​​of the glass bulk material increase, deteriorating the color balance. In addition, the refractive index (n d For example, high refractive index glass with a refractive index of 1.78 or more has poor light transmittance in the short wavelength region, so the ISO / CCI G and R values ​​of the glass bulk material are large and the color balance is not good.

[0026] However, optical glass for manufacturing wearable devices and mobile devices, which do not necessarily require a high refractive index, can reduce the ISO / CCI B value of the glass bulk material as well as the G value and R value, ensuring good color balance and making it possible to obtain optical glass with a color characteristic index with a low degree of color change. Furthermore, optical elements manufactured using optical glass with a color characteristic index with a low degree of color change can provide users with images and videos that are closer to the actual colors, and are therefore suitable for wearable applications such as AR, VR, and MR, as well as for mobile device applications.

[0027] For these reasons, the optical glass according to the present invention has color characteristics expressed by ISO / CCI when converted into a 10 mm thick plate, of 0.00 for blue (B) and 0.80 or less for green (G). This value is more preferably 0.70 or less, and even more preferably 0.60 or less. Moreover, the value is 0.80 or less for red (R). This value is also more preferably 0.70 or less, and even more preferably 0.60 or less.

[0028] 2. Mechanical properties (thermal shock resistance) In general, the stress (σ) generated in a glass bulk material due to thermal shock can be predicted by the following formula.

[0029] σ=λ E α ΔT / (1-ν)

[0030] Here, λ is a constant related to the shape of the glass and the rate of heat transfer, E is Young's modulus (GPa), and α is the average linear expansion coefficient (10 -7 ℃ -1 ), ΔT is the temperature difference, and ν is Poisson's ratio.

[0031] As mentioned above, ΔT is a temperature difference and is therefore a parameter of the manufacturing process, not a property of the glass bulk material. Therefore, the three values ​​that are highly dependent on the glass composition are Young's modulus (E), the average linear expansion coefficient in the temperature range of 100°C to 300°C (α), and Poisson's ratio (ν).

[0032] In order to enhance the thermal shock resistance of optical glass, it is particularly desirable for S=E·α / (1-ν) to be low. In the specification of Japanese Patent No. 4537317, the applicant of the present application also stated that, from the viewpoint that obtaining a glass material with both a small Young's modulus (E) and a small average linear expansion coefficient (α) is an important point for producing optical glass with high thermal shock resistance, the value of S=E·α / (1-ν) should be 1.00×10 6 ~1.35×10 6 (Pa·℃ -1 The reason why such high thermal shock resistance is required is that optical glass is required to have high thermal shock resistance so that cracks and chips do not occur during the manufacturing process of optical elements, such as mold press molding, even if there are drastic temperature changes, such as rapid temperature increases and decreases.

[0033] Recent wearable and mobile devices generate heat rapidly during operation, so the thermal shock resistance of conventional glass is sometimes insufficient, making it necessary to adopt glass with higher thermal shock resistance.

[0034] Therefore, in the present invention, the value of S calculated by the following formula (1) is 0.70×10 6 More than 1.03 x 10 6By adjusting the composition so that the thermal expansion coefficient is in the range of less than (Pa / °C), the production stability and moldability of the optical glass are improved. Designing it in this range results in an optical glass with a suitable thermal expansion coefficient, excellent moldability, and less susceptible to cracking or chipping during the manufacturing process. On the other hand, if this value is too large, the risk of frequent manufacturing defects due to cracking or chipping increases significantly, so the upper limit is set to 1.03×10 6 (Pa / ℃).

[0035] The optical glass of the present invention can be suitably used as a light guide plate. When the optical glass of the present invention is used as a light guide plate, the glass is laminated together, and the difference in the average linear expansion coefficient between the laminated glasses (hereinafter referred to as substrate 1, substrate 2, ... substrate n) is within ±3.0 × 10 -7 The difference in the average linear expansion coefficient of the substrates 1 to n is preferably ±3.0×10 -7 Less than or equal to ±2.0×10 -7 Less than or equal to ±1.0×10 -7 The upper limit is as follows: Since the difference in linear expansion between substrates 1 to n is small, even when heat is applied to the light guide plate, it is possible to suppress misalignment or peeling caused by the difference in linear expansion between the joined glasses.

[0036] S = E α / (1 - ν) Equation (1) In formula (1), E is Young's modulus (unit: GPa), α is the average linear expansion coefficient (unit: 10 -7 ℃ -1 ), and ν is Poisson's ratio.

[0037] Above S value 0.70 x 10 6 More than 1.03 x 10 6 Less than (Pa / °C) is the S value (1.00×10 6 ~1.35×10 6 (Pa·℃ -1As a result, the optical glass according to the present invention is less susceptible to cracking or chipping during the manufacturing process, which makes it possible to improve the production stability and moldability of the optical glass.

[0038] As described above, in the present invention, the value of S is 0.70×10 6 More than 1.03 x 10 6 The composition is adjusted so that the S value is in the range of less than 0.73 × 10 6 (Pa / ℃) or more, and more preferably 0.75×10 6 (Pa / ℃) or more, and more preferably 0.80×10 6 (Pa / °C) or more. The upper limit of the S value is preferably 1.00×10 6 (Pa / ℃), more preferably less than 0.98×10 6 (Pa / °C). For example, in a preferred embodiment, the S value is less than 0.73 × 10 6 Above 1.00 x 10 6 The range is less than (Pa / ℃).

[0039] 3. Refractive index (n d ) The optical glass of the present invention has a refractive index (n d ) has a lower limit of 1.45000 and an upper limit of 1.65000, that is, in the range of 1.45000 to 1.65000. As already explained, the refractive index of the optical glass disclosed in JP 2021-102549 A is 1.95 or more, and the refractive index of the optical glass disclosed in JP 2021-31378 A is in the range of 1.90 to 2.10. Therefore, the refractive index (n d ) is considerably lower than that of conventional optical glasses for wearable applications. This is the result of the present invention being made based on the viewpoint that, as described above, in optical glasses for manufacturing wearable devices and mobile devices, which do not necessarily require a high refractive index, it is required to have a color characteristic index with a low degree of color change and excellent color correction over a wide range, rather than the refractive index itself.

[0040] Depending on the configuration and design freedom of the optical element in which the optical glass according to the present invention is used, the refractive index (n d The lower limit of the refractive index (n d ) may be 1.64000 or less, 1.63000 or less, 1.62000 or less, or 1.61000 or less.

[0041] 4.Optical homogeneity Non-uniformity of the refractive index inside optical glass has a significant effect on the optical characteristics, and is a cause of deterioration of the characteristics of optical elements. In this regard, the optical glass according to the present invention has high homogeneity, and as a result, has an excellent refractive index distribution. The refractive index distribution of the optical glass of the present invention is preferably within 0.00050, more preferably within 0.00030, even more preferably within 0.00010, even more preferably within 0.00007, and even more preferably within 0.00005. The homogeneity of the refractive index is measured, for example, using a Fizeau-type optical interferometer by the oil-on-plate method or the polished homogeneous method, by determining the PV value: Δn of the refractive index fluctuation width excluding the linear change component of the refractive index, of the amount of change in the refractive index within the surface to be measured. PV Request.

[0042] 5. Abbe number The Abbe number (reverse dispersion rate) is an index for evaluating the chromatic dispersion (change in refractive index with wavelength) of a transparent body, and a large Abbe number indicates a small dispersion. The Abbe number of the optical glass according to the present invention is significantly lower than that of conventional ones, and the lower limit is preferably 35.00 or more, more preferably 38.00 or more, even more preferably 40.00 or more, and even more preferably 42.00 or more. On the other hand, the upper limit of the Abbe number is preferably 70.00 or less, more preferably 68.00 or less, even more preferably 67.00 or less, and even more preferably 65.00 or less.

[0043] 6.Specific gravity There is no particular restriction on the specific gravity of the optical glass according to the present invention, but from the viewpoint of reducing the weight of the optical element, it is preferably 4.50 or less, more preferably 4.00 or less, even more preferably 3.80 or less, and even more preferably 3.50 or less.

[0044] 7. Ratio of specific gravity and refractive index The optical glass of the present invention has a specific gravity d and a refractive index n d The ratio of d / n is preferably d <2.1, more preferably d / n d <2.0, more preferably d / n d <1.9. Glass materials that satisfy these requirements are advantageous as glass materials for the optical elements of the present invention, such as the lenses for smartphones and the prisms of periscope cameras. For example, there are two ways to reduce the weight of a prism: using glass with a relatively high refractive index to reduce the volume of the prism, or using glass that has a low specific gravity to begin with. The present invention adopts the latter method. In that case, d / n d A preferred range for is less than 2.1, more preferably less than 2.0, even more preferably less than 1.9, and most preferably less than 1.85.

[0045] 8. Composition The composition of the optical glass according to the present invention will be described below. Unless otherwise specified, the content of each component will be expressed in mole percent. In this specification, "substantially free" means that it is not blended as a raw material component, that is, it is not intentionally included, and does not exclude substances that may be mixed in as impurities.

[0046] As described later, in one embodiment, the optical glass according to the present invention contains, in mole percent on an oxide basis, a total content of TiO2 component, Nb2O5 component, Bi2O3 component, and WO3 component of 10.0% or less, and contains, in mole percent on an oxide basis, 30.0 to 80.0% of a SiO2 component and 0.00 to 30.0% of a B2O3 component (however, the sum of the SiO2 component and the B2O3 component does not exceed 100.0%).

[0047] In this specification, the term "oxide basis" refers to a composition in which each component contained in the glass is expressed based on the assumption that oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituent components of the present invention are all decomposed and converted to oxides during melting, with the total weight of the generated oxides being taken as 100 mol %.

[0048] SiO2 component: The SiO2 component is a glass-forming component that imparts high strength, glass stability, and chemical durability, and improves moldability. It can also reduce expansion. The lower limit of the SiO2 component content is preferably 40% or more, and more preferably 43% or more, 45% or more, 48% or more, and 50% or more in this order. The upper limit of the SiO2 component content is preferably 90% or less, and more preferably 85% or less, 80% or less, 78% or less, and 75% or less in this order.

[0049] Na2O component: The Na2O component is a component that enhances the meltability and moldability of glass. On the other hand, if the content is high, the impact resistance decreases. The optical glass of the present invention may be an optical glass that does not substantially contain the Na2O component (0%), but if it is contained, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. The content of the Na2O component is preferably an upper limit of 20% or less, and more preferably 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, and 10% or less in this order.

[0050] BaO component: The BaO component is a component that enhances the meltability of optical glass and increases the refractive index of the glass. On the other hand, if the content is high, the impact resistance decreases. The optical glass of the present invention may be an optical glass that does not substantially contain a BaO component (0%), but if it is contained, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. The content of the BaO component is preferably an upper limit of 30% or less, and more preferably 28% or less, 25% or less, and 20% or less in this order.

[0051] B2O3 component: B2O3 component is a glass forming component, which improves devitrification resistance and improves moldability. It can also reduce expansion. The optical glass of the present invention may be an optical glass that does not substantially contain B2O3 component (0%), but if it does contain B2O3 component, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, 0.8% or more, and 1.0% or more in this order. The content of B2O3 component is preferably 30% or less in upper limit, and more preferably 25% or less, 23% or less, and 20% or less in this order.

[0052] K2O component: The K2O component is a component that enhances the meltability and moldability of optical glass. On the other hand, if the content is high, the impact resistance decreases. The optical glass of the present invention may be an optical glass that does not substantially contain the K2O component (0%), but if it is contained, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. The content of the K2O component is preferably an upper limit of 20% or less, and more preferably 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, and 10% or less in this order.

[0053] Li2O component: The Li2O component is a component that enhances the meltability and moldability of optical glass. On the other hand, if the content is high, the impact resistance decreases. The optical glass of the present invention may be an optical glass that does not substantially contain the Li2O component (0%), but if it is contained, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. The content of the Li2O component is preferably an upper limit of 20% or less, and more preferably 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, and 10% or less in this order.

[0054] Al2O3 component: The Al2O3 component is a component that enhances the impact resistance and devitrification resistance of optical glass and reduces the expansion of the glass. It is also a component that suppresses phase separation of the glass and enhances devitrification resistance. The optical glass of the present invention may be an optical glass that does not substantially contain the Al2O3 component (0%), but if it does contain the Al2O3 component, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. The content of the Al2O3 component is preferably an upper limit of 10% or less, and more preferably 8% or less, 6% or less, and 5% or less in this order.

[0055] TiO2 component: The TiO2 component is a component that increases the refractive index of the glass. On the other hand, if the content is high, it will cause the glass to become colored. The optical glass of the present invention may be an optical glass that does not substantially contain the TiO2 component (0%), but if it does contain the TiO2 component, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. The content of the TiO2 component is preferably an upper limit of 20% or less, and more preferably 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, and 10% or less in this order.

[0056] Nb2O5, Bi2O3, WO3 components: Nb2O5, Bi2O3, and WO3 components are components that improve the refractive index of glass. On the other hand, if the content is high, the glass will be colored. The optical glass of the present invention may be an optical glass that does not substantially contain Nb2O5, Bi2O3, and WO3 components (0%), but if they are contained, the lower limit of each component is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. In addition, the content of Nb2O5, Bi2O3, and WO3 components is preferably 10% or less in the upper limit, and more preferably 8% or less, 5% or less, 3% or less, 2% or less, and 1% or less in this order.

[0057] CaO component: The CaO component is a component that enhances meltability and increases the refractive index of the glass. On the other hand, if the content is high, the impact resistance decreases. The optical glass of the present invention may be an optical glass that does not substantially contain CaO (0%), but if it does contain CaO, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. The content of the CaO component is preferably an upper limit of 30% or less, and more preferably 28% or less, 25% or less, and 20% or less in this order.

[0058] ZnO component: ZnO component is a component that enhances melting property and increases the refractive index of glass. On the other hand, if the content is high, impact resistance decreases. The optical glass of the present invention may be an optical glass that does not substantially contain ZnO (0%), but if it is contained, the lower limit is preferably more than 0%, and more preferably 0.1% or more, 0.5% or more, and 1.0% or more in this order. In addition, the upper limit of the content of the ZnO component is preferably 10% or less, and more preferably 8% or less, 5% or less, 3% or less, 2% or less, and 1% or less in this order.

[0059] ZrO2 component: ZrO2 component can be added for the purpose of adjusting optical constants and improving durability of glass. However, since it may deteriorate stability as glass, it is preferable that it is not substantially contained, but if it is contained, the upper limit is preferably 5.0% or less, and more preferably 4.0% or less, 3.0% or less, 2.0% or less, and 1.0% or less in that order.

[0060] F component: The F component is effective for obtaining a high transmittance, and can also provide an optical glass having a low transition temperature (Tg).

[0061] In the optical glass of the present invention, the F component is considered to exist in the form of a fluoride in which the oxygen atoms of one or more oxides of silicon or other metal elements are substituted for part or all of the oxygen atoms. If the total amount of F in the fluorides in which the oxygen atoms of the oxides are substituted for part or all of the oxygen atoms is too large, the amount of volatilization of the fluorine component increases, making it difficult to obtain a homogeneous glass, and therefore, in cases where stable production is hindered, it should not be added. Therefore, in the present invention, the upper limit is preferably 5.0% or less, more preferably 3.0% or less, 1.0% or less, 0.5% or less, and 0.3% or less, in that order, based on the oxide, and an embodiment in which the F component is substantially not contained may be adopted.

[0062] Ta2O5 component: The Ta2O5 component is a component that increases the refractive index of glass and increases the devitrification resistance of glass. On the other hand, by making the content of the Ta2O5 component 5.0% or less, the amount of the Ta2O5 component, which is a rare mineral resource, used is reduced, and the glass is more easily melted at a lower temperature, so that the production cost of the glass can be reduced. This also makes it possible to reduce devitrification of the glass caused by the excessive inclusion of the Ta2O5 component. Therefore, the upper limit of the content of the Ta2O5 component is preferably 5.0% or less, more preferably 3.0% or less, and even more preferably 1.0% or less, but it may be 0%.

[0063] P2O5 component: The upper limit of the content of the P2O5 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%.

[0064] TeO2 component: The upper limit of the content of the TeO2 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%.

[0065] Ga2O3 component: The upper limit of the Ga2O3 component content 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%.

[0066] GeO2 component: The upper limit of the content of the GeO2 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%.

[0067] CeO2 component: The upper limit of the content of the CeO2 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%.

[0068] Er2O3 component, Pr2O3 component: The content of the Er2O3 component and the Pr2O3 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.

[0069] SnO2 component: The upper limit of the content of the SnO2 component is preferably 2.0% or less, more preferably 1.0% or less, and further preferably 0.5% or less, but may be 0%.

[0070] Sb2O3 component: The Sb2O3 component is an optional component that promotes clarification and defoaming when melting glass. By making the content of the Sb2O3 component 0.1% or less, it is possible to suppress coloring, particularly in high refractive index glass. Furthermore, by making the content 0.1% or less, excessive foaming during glass melting is unlikely to occur, making it difficult for the Sb2O3 component to be alloyed with the melting equipment (particularly precious metals such as Pt). Therefore, the upper limit of the content of the Sb2O3 component is preferably 0.1% or less, more preferably 0.08% or less, and even more preferably 0.05% or less, but it may be 0%.

[0071] The component for clarifying and defoaming the glass is not limited to the above Sb2O3 component, but any fining agent, defoaming agent or combination thereof known in the field of glass manufacturing can be used.

[0072] C component: The C component is a component that can maintain a reducing atmosphere in the platinum crucible, suppress the incorporation of platinum into the glass due to oxidation, and improve the transmittance, but if the content is high, the cationic components in the glass are reduced, causing coloring of the glass. Therefore, the content of the C component is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less as the upper limit. On the other hand, the content of the C component is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 2.0% or more as the lower limit, but may be 0%.

[0073] S component: The S component is a component that can maintain a reducing atmosphere in the platinum crucible, suppress the incorporation of platinum into the glass due to oxidation, and improve the transmittance, but if the content is high, the cationic components in the glass are reduced, causing coloring of the glass. Therefore, the upper limit of the S component content is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less. On the other hand, the lower limit of the S component content is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 2.0% or more, but it may be 0%.

[0074] Organic components such as sucrose: Organic components such as sucrose are components that can maintain a reducing atmosphere in the platinum crucible, suppress the incorporation of platinum into the glass due to oxidation, and improve the transmittance, but if the content is high, the cationic components in the glass are reduced, causing coloring of the glass. Therefore, the content of organic components such as sucrose is preferably 10.0% or less, more preferably 8.0% or less, more preferably 6.0% or less, and most preferably 5.0% or less as the upper limit. On the other hand, the content of organic components such as sucrose is preferably more than 0%, more preferably 0.5% or more, even more preferably 1.0% or more, and most preferably 2.0% or more as the lower limit, but may be 0%.

[0075] The components that reduce cations in glass are not limited to the above-mentioned C component, S component, and organic components such as sucrose, and any reducing agent known in the field of glass manufacturing or a combination thereof can be used.

[0076] By setting the total content of TiO2, Nb2O5, Bi2O3, and WO3 to 10.0% or less, the refractive index can be reduced while suppressing an increase in specific gravity. Therefore, the upper limit of the total content of TiO2, Nb2O5, Bi2O3, and WO3 is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, and even more preferably 1.0% or less.

[0077] The sum of the contents (molar sum) of the Ln2O3 components (wherein Ln is one or more selected from the group consisting of La, Y, Gd, and Yb) can increase the refractive index of the glass, but if contained in excess, it increases the devitrification tendency of the glass. Therefore, the upper limit of the sum of the contents of the Ln2O3 components 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 even more preferably 1.0% or less.

[0078] The sum of the contents (molar sum) of Rn2O components (wherein Rn is one or more selected from the group consisting of Li, Na, and K) is a component that can improve the meltability of glass, but if contained in excess, it will deteriorate the devitrification resistance during processing. By improving the meltability of glass, glass with good productivity can be obtained. Therefore, the upper limit of the sum of the contents of Rn2O components is preferably 20.0% or less, more preferably 18.0% or less, and even more preferably 16.0% or less. On the other hand, the lower limit of the sum of the contents of Rn2O components is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.2% or more, even more preferably 0.3% or more, and even more preferably 0.4% or more.

[0079] The sum of the contents (molar sum) of RO components (wherein R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is a component that enhances the stability of the glass, but when contained in excess, it is a component that causes a decrease in the refractive index. Therefore, the upper limit of the sum of the contents of RO components is 30.0% or less, more preferably 28.0% or less, even more preferably 26.0% or less, and even more preferably 25.0% or less. On the other hand, the lower limit of the sum of the contents of RO components is preferably more than 0%, more preferably 0.1% or more, even more preferably 0.3% or more, even more preferably 0.4% or more, and even more preferably 0.5% or more.

[0080] By setting the molar sum Rn2O+RO, which is the total content of the Rn2O component and the RO component, to 10.0% or more, it is possible to obtain a glass that has high meltability and is stable. Therefore, the lower limit of the molar sum Rn2O+RO is preferably 10.0% or more, more preferably 12.0% or more, even more preferably 13.0% or more, even more preferably 14.0% or more, and even more preferably 15.0% or more. On the other hand, by setting the molar sum Rn2O+RO to 40.0% or less, it is possible to suppress an excessive decrease in the refractive index. Therefore, the upper limit of the molar sum Rn2O+RO is preferably 40.0% or less, more preferably 38.0% or less, even more preferably 35.0% or less, even more preferably 33.0% or less, and even more preferably 30.0% or less.

[0081] Chemical durability can be improved by setting the molar ratio (SiO2+B2O3+Al2O3) / (Rn2O+RO) of the total content of SiO2, B2O3, and Al2O3 to the molar sum Rn2O+RO of the total content of Rn2O and RO components at 1.00 or more. Therefore, the lower limit of the molar ratio (SiO2+B2O3+Al2O3) / (Rn2O+RO) is preferably 1.00 or more, more preferably 1.30 or more, even more preferably 1.50 or more, even more preferably 1.80 or more, and even more preferably 2.00 or more. On the other hand, meltability can be maintained by setting the molar ratio (SiO2+B2O3+Al2O3) / (Rn2O+RO) to 7.00 or less. Therefore, the upper limit of the molar ratio (SiO2+B2O3+Al2O3) / (Rn2O+RO) is preferably 7.00 or less, more preferably 6.80 or less, even more preferably 6.50 or less, even more preferably 6.30 or less, and even more preferably 6.00 or less.

[0082] <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.

[0083] 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.

[0084] Furthermore, since lead compounds such as PbO and arsenic compounds such as As2O3 are components that have a high environmental impact, it is desirable that they are not contained substantially, that is, that they are not contained at all except for unavoidable contamination.

[0085] 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.

[0086] In one embodiment, the optical glass according to the present invention contains, in mole percent on an oxide basis, a TiO2 component, a Nb2O5 component, a Bi2O3 component, and a WO3 component in a total content of 10.0% or less.

[0087] In one embodiment, the optical glass according to the present invention contains, in mole percent on an oxide basis, 30.0 to 80.0% of SiO2 component and 0.00 to 30.0% of B2O3 component, provided that the sum of the SiO2 component and the B2O3 component does not exceed 100.0%.

[0088] 9. Manufacturing method The optical glass of the present invention is produced, for example, as follows. That is, the above-mentioned raw materials are mixed uniformly so that each component falls within a predetermined content range, the mixture produced is put 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, then cooled to an appropriate temperature, cast into a mold, and slowly cooled to produce the glass. In particular, the optical glass of the present invention is preferably produced by lowering the layer speed in the molding process from the viewpoint of reducing distortion. Specifically, it is preferably 400mm / min, more preferably 300mm / min, and even more preferably 220mm / min.

[0089] The optical glass described above has a refractive index (n d The present invention provides an optical glass having a color characteristic index with a relatively low range compared to conventional ones and a low degree of color change, and thus provides an optical glass with excellent production stability, moldability, and color correction over a wide range.

[0090] [B: Optical element made of the optical glass of the present invention] The optical glass according to the present invention is suitable for optical element applications that do not require a high refractive index, and is particularly suitable for wearable applications such as AR, VR, and MR, as well as mobile device applications. Examples include wearable applications such as glasses with projectors, eyeglass-type and goggle-type displays, virtual reality and augmented reality displays, and virtual image displays, as well as mobile device applications such as mobile phones and smartphones. These optical elements may be optical elements used together with, for example, a transparent resin plate or a curable resin material. EXAMPLES

[0091] Table 1 shows the compositions of the optical glasses of Examples 1 to 9, and Table 2 shows the physical property data.

[0092] For the glasses of the examples of the present invention, high purity raw materials used in ordinary optical glass, such as the corresponding oxides, hydroxides, carbonates, nitrates, fluorides, and metaphosphate compounds, were selected as the raw materials for each component, and these were weighed out and mixed uniformly to obtain the composition ratios of each of Examples 1 to 9 shown in Table 1 below. The mixture was then placed in a platinum crucible and melted in an electric furnace at a temperature range of 1000 to 1500°C for 2 to 4 hours depending on the melting difficulty of the glass composition. The mixture was then stirred and homogenized, and poured into a mold or the like, and slowly cooled to produce the glass.

[0093] 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 (nd ), Abbe number (ν d ) was determined by measuring the glass obtained by cooling at a rate of -25°C / hr.

[0094] The ISO color characteristic index (ISO / CCI) of the glass in the examples was measured as follows: With reference to JIS B7097 (how to express color characteristics for photography using the ISO color characteristic index (ISO / CCI)), the G value (green) and R value (red) were calculated to two decimal places when B (blue) was set to 0.

[0095] The Young's modulus (E), modulus of rigidity (G) and Poisson's ratio (ν) of the glass in the examples were measured by an ultrasonic pulse method using a sample of 100×10×10 mm.

[0096] The average linear expansion coefficient (α) of the glasses in the examples was determined at −30 to 70° C. and 100 to 300° C. in accordance with the Japan Optical Glass Industry Association standard JOGIS16-2019 “Method for measuring the average linear expansion coefficient of optical glass near room temperature.”

[0097] 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 Z8807:2019.

[0098] The physical property data of the optical glasses of Examples 1 to 9 obtained by the above-mentioned methods are summarized in Table 2.

[0099]

Table 1

[0100]

Table 2

[0101] As described above, optical glass for manufacturing wearable devices and mobile devices, which do not necessarily require a high refractive index, does not require a high refractive index, so the optical glass of the present invention can reduce not only the ISO / CCI B value of the glass bulk material, but also the G value and R value, ensuring good color balance and making it possible to obtain an optical glass having a color characteristic index with a low degree of color change. Furthermore, optical elements manufactured using optical glass having such a color characteristic index with a low degree of color change can provide users with images and videos that are closer to the actual colors, and are therefore suitable for wearable applications such as AR, VR, and MR, as well as for mobile device applications. [Industrial Applicability]

[0102] According to the present invention, the refractive index (n d The present invention provides an optical glass having a color characteristic index with a relatively low range compared to conventional ones and a low degree of color change, and is excellent in production stability, moldability, and color correction over a wide range. Such an optical glass is suitable for wearable applications such as AR, VR, and MR, as well as for mobile devices.

Claims

1. The refractive index (n ｄ ) is in the range of 1.45000 to 1.65000, The ISO color characteristic index ISO / CCI is in the range of 0.00 for blue (B), 0.80 or less for green (G), and 0.80 or less for red (R); The value of S calculated by the following formula (1) is 0.70 × 10 ６ Above 1.03 x 10 ６ An optical glass having a modulus of elasticity in the range of less than (Pa / °C). S=E・α / (1-ν) ... Formula (1) E: Young's modulus (unit: GPa) α: Average linear expansion coefficient in the temperature range of 100°C to 300°C (unit: 10 －７ ℃ －１ ) ν: Poisson's ratio

2. The refractive index (n ｄ 2. The optical glass according to claim 1, wherein the upper limit of σ is 1.64000.

3. 2. The optical glass of claim 1, wherein the ISO color characteristic index ISO / CCI is in the range of 0.00 for blue (B), 0.70 or less for green (G), and 0.70 or less for red (R).

4. The value of S is 0.73×10 ６ Above 1.00 x 10 ６ The optical glass according to claim 1 , wherein the modulus of elasticity is in the range of less than (Pa / ° C.).

5. In mole percent based on oxide, TiO ２ Component: Nb ２ O ５ Component: Bi ２ O ３ Ingredients, and WO ３ 2. The optical glass according to claim 1, wherein the total content of the components is 10.0% or less.

6. In mole percent based on oxide, SiO ２ Ingredients: 30.0-80.0%, B ２ O ３ Contains 0.00 to 30.0% of the component (however, SiO ２ Ingredients and B ２ O ３ The optical glass of claim 1 , wherein the sum of the components does not exceed 100.0%.

7. An optical element comprising the optical glass according to any one of claims 1 to 6.

8. 8. The optical element according to claim 7, which is used together with a transparent resin plate or a curable resin material.

9. The optical element according to claim 7 , which is used in a wearable device or a mobile device.

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