Uv-c transmitting glass and glass components

Abstract

This invention provides a UV-C transmissive glass with good melting properties, low thermal expansion coefficient, and excellent water resistance in a specific composition of aluminoborate glass. The UV-C transmissive glass is characterized by comprising, by mass%,: 46.90% to less than 55.00% SiO2; greater than 27.00% to less than 35.10% B2O3; 6.90% to less than 12.00% Al2O3; 0.90% to less than 8.00% Li2O; 0.90% to less than 8.10% Na2O; 0% to less than 5.10% K2O; 4.00% to less than 9.00% R2O, wherein R2O represents the sum of Li2O, Na2O, and K2O; and 0% to less than 3%. The following are the contents of the following: MgO (0.00% or less); CaO (0% or more and 3.00% or less); SrO (0% or more and 4.00% or less); BaO (0% or more and 4.00% or less); R'O (0% or more and less than 5.00%, where R'O represents the sum of MgO, CaO, SrO and BaO); Sb2O3 (0% or more and 1.00% or less); F (0.01% or more and 1.00% or less); Cl (0.05% or more and 1.00% or less); and the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is less than 0.1.

Description

Technical Field

[0001] This invention relates to UV-C transmission glass and glass components. Background Technology

[0002] In the past, low-pressure mercury lamps emitting ultraviolet light at 184.9nm and 253.7nm were used as light sources for sterilization. However, according to the Minamata Convention on Mercury, signed in 2013, the manufacture, import and export of mercury-containing products have been prohibited since 2021, with the exception of certain applicable products. Therefore, there is a growing expectation for UV-C LEDs (deep ultraviolet LEDs) as a replacement for low-pressure mercury lamps, as they pose less risk to humans and the environment. Moreover, the spread of the COVID-19 pandemic has created an opportunity to increase the need for on-site sterilization of items that have been touched by an uncertain number of people, and UV-C LEDs, which are easy to use and compact, are rapidly gaining popularity in a new market.

[0003] However, compared to the output of several watts to tens of watts per mercury lamp, the output of each UV-C LED element is several milliwatts to tens of milliwatts. Therefore, from an output perspective, UV-C LEDs are still in the development stage. In the future, with improvements in electrical and optical power generation efficiency, if the output of UV-C LEDs exceeds 100 milliwatts, UV-C LEDs will have extremely strong bactericidal effects and can be installed in large-scale UV-C devices that currently rely on mercury lamps.

[0004] With the increasing output of UV-C LEDs, the durability of UV-C LED packages is crucial. Window components with shapes such as flat plates or lenses are used in UV-C LED packages. Lens-shaped window components protect the UV-C LED chip from external air and also allow for control of the light emitted from the UV-C LED, ensuring efficient UV-C illumination.

[0005] Quartz glass, with its excellent UV-C transmittance and durability, is suitable as the window component for UV-C LED packaging. However, the manufacture of quartz glass requires melting the raw material at temperatures above 2000°C. Furthermore, the processing of quartz glass is based on cutting from a blank (crystallized block). The grinding process involves mechanical processing. Therefore, quartz glass presents problems in terms of productivity and processability.

[0006] On the other hand, aluminoborosilicate glass has a lower melting temperature than quartz glass, and also exhibits high transmittance over a wide wavelength range. Therefore, aluminoborosilicate glass has the potential to be useful as a glass for UV-C LED packaging.

[0007] For example, patent documents 1-4 disclose aluminum borosilicate glasses that are transmissive to ultraviolet light.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 4-342437

[0011] Patent Document 2: Japanese Patent Application Publication No. 2018-197190

[0012] Patent Document 3: Japanese Patent Application Publication No. 2012-140314

[0013] Patent Document 4: Japanese Patent Application Publication No. 2013-230952 Summary of the Invention

[0014] The problem the invention aims to solve

[0015] From a productivity standpoint, good meltability is crucial for UV-C transmission glass. However, the glass disclosed in Patent Document 1 has poor meltability, requiring the raw materials to be melted at high temperatures during its manufacture. Furthermore, poor meltability leads to poor defoaming, potentially resulting in residual air bubbles within the glass. Additionally, the glass disclosed in Patent Document 2, which preferably contains 60-68% by mass of SiO2 as a main component, may also exhibit poor meltability due to the large amount of SiO2.

[0016] The low thermal expansion coefficient of UV-C transmission glass is crucial. For example, in the packaging of UV-C LEDs, ceramics with high thermal conductivity, such as aluminum nitride (AlN) and alumina (Al2O3), are typically used as the housing material. Since the thermal conductivity of glass differs significantly from that of ceramics, the temperature difference between the glass and the housing increases when heat is applied to bond them together. Therefore, if the thermal expansion coefficient of the glass is high, there is a possibility of strain occurring within the glass, leading to breakage. However, Patent Documents 3 and 4 do not address the thermal expansion coefficient at all.

[0017] Because it is required to function as a sealing material to protect the UV-C LED chip from moisture and other external elements, good water resistance is also crucial for the UV-C transmission glass. Furthermore, if the glass has poor water resistance, it will react with water, causing cloudiness and potentially reducing the transmittance of UV-C. However, Patent Documents 2 and 4 make no mention of water resistance.

[0018] In view of the above, for UV-C transmission glass, it is required, in particular, to meet all the requirements such as good melting properties, low thermal expansion coefficient and excellent water resistance through composition optimization.

[0019] Therefore, the present invention is made in view of the actual situation described above, and the object of the present invention is to provide a UV-C transmission glass with good melting properties, low thermal expansion coefficient and excellent water resistance in a specific composition of aluminoborosilicate glass.

[0020] Furthermore, the object of the present invention is to provide a glass component using the aforementioned UV-C transmissive glass.

[0021] means for solving problems

[0022] Through dedicated research in order to achieve the above objectives, the inventors discovered that the above objectives could be achieved in a specific composition of aluminoborosilicate glass, thus completing this invention.

[0023] The technical solution of the present invention that solves the above problems is as follows.

[0024] [1] A UV-C transmission glass, characterized in that, The UV-C transmission glass comprises, by weight%, SiO2: 46.90% or more but less than 55.00%; B2O3: greater than 27.00% and less than 35.10%; Al2O3: 6.90% or more and 12.00% or less; Li2O: ≥0.90% and ≤8.00%; Na2O: ≥0.90% and ≤8.10%; K2O: 0% or more and 5.10% or less; R2O: 4.00% or more and less than 9.00% (where R2O represents the sum of Li2O, Na2O and K2O); MgO: ≥0% and ≤3.00%; CaO: 0% or more and 3.00% or less; SrO: 0% or more and 4.00% or less; BaO: 0% or more and 4.00% or less; R'O: 0% or more and less than 5.00% (where R'O represents the sum of MgO, CaO, SrO and BaO); Sb2O3: ≥0% and ≤1.00%; F: Greater than 0.01% and less than 1.00%; Cl: ≥0.05% and ≤1.00%; and The mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is less than 0.1.

[0025] [2] As described in [1], the UV-C transmission glass has an average linear expansion coefficient (α) 100-300℃ ) is 45×10 -7 / ℃ or above and 60×10 -7 / ℃ below.

[0026] [3] The UV-C transmission glass described in [1] or [2] has an internal transmittance of more than 90% at a wavelength of 265 nm within a glass thickness of 1 mm.

[0027] [4] The UV-C transmission glass as described in any one of [1] to [3] has a glass transition temperature of 510°C or less.

[0028] [5] The UV-C transmission glass as described in any one of [1] to [4], when the glass sheet is set to 20mm×10mm×10mm and the glass sheet is boiled in 1000ml of pure water for 60 minutes, the weight loss before and after the boiling treatment is less than 0.1 mass.

[0029] [6] The UV-C transmission glass as described in any one of [1] to [5] is used for precision molding.

[0030] [7] A glass component, characterized in that it uses UV-C transmission glass as raw material as described in any one of [1] to [6].

[0031] Invention Effects

[0032] Based on the present invention, a UV-C transmission glass with good melting properties, low thermal expansion coefficient and excellent water resistance in a specific composition of aluminoborosilicate glass can be provided.

[0033] Furthermore, based on the present invention, it is possible to provide a glass component using the aforementioned UV-C transmissive glass. Detailed Implementation

[0034] (UV-C transmission glass)

[0035] Hereinafter, a UV-C transmission glass (hereinafter sometimes referred to as "the glass of this embodiment") according to an embodiment of the present invention will be specifically described.

[0036] The glass in this embodiment is characterized in that, Included by mass% SiO2: 46.90% or more but less than 55.00%; B2O3: greater than 27.00% and less than 35.10%; Al2O3: 6.90% or more and 12.00% or less; Li2O: ≥0.90% and ≤8.00%; Na2O: ≥0.90% and ≤8.10%; K2O: 0% or more and 5.10% or less; R2O: 4.00% or more and less than 9.00% (where R2O represents the sum of Li2O, Na2O and K2O); MgO: ≥0% and ≤3.00%; CaO: 0% or more and 3.00% or less; SrO: 0% or more and 4.00% or less; BaO: 0% or more and 4.00% or less; R'O: 0% or more and less than 5.00% (where R'O represents the sum of MgO, CaO, SrO and BaO); Sb2O3: ≥0% and ≤1.00%; F: Greater than 0.01% and less than 1.00%; Cl: 0.05% or more and 1.00% or less (A necessary condition for constituting this).

[0037] Furthermore, a characteristic of the glass of this embodiment is that the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is less than 0.1. The glass of this embodiment was discovered through repeated experiments by the inventors. By satisfying the above-mentioned necessary compositional conditions and by having a mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) less than 0.1, a UV-C transmission glass with good melting properties, low thermal expansion coefficient, and excellent water resistance within a specific composition of aluminoborosilicate glass can be provided.

[0038] The reasons for limiting the range of each component as a necessary condition for composition are explained below. Additionally, unless otherwise specified, "%" in relation to a component means "mass %".

[0039] <sio2>

[0040] SiO2 is an essential component of the glass of this embodiment and is the main component forming the glass's network structure. SiO2 is a component that can reduce the coefficient of thermal expansion and improve water resistance. Furthermore, SiO2 can improve anti-devitrification stability. However, if the SiO2 content is 55.00% or more, there is a possibility that the viscosity of the glass melt increases and its solubility decreases significantly. On the other hand, if the SiO2 content is less than 46.90%, there is a possibility that the effects of reducing the coefficient of thermal expansion and improving water resistance cannot be sufficiently obtained. Additionally, there is a possibility that the effect of improving anti-devitrification stability cannot be obtained. Therefore, in the glass of this embodiment, the SiO2 content is set to a range of 46.90% or more and less than 55.00%. From the same viewpoint, the SiO2 content of the glass of this embodiment is preferably 47.00% or more, and more preferably 54.90% or less.

[0041] <b2o3>

[0042] In the optical glass of this embodiment, B2O3, like SiO2, is a component that forms the network structure of the glass. B2O3 is a component that can reduce the viscosity of the glass melt and improve its melt permeability without causing a change in the thermal expansion coefficient of the glass. Furthermore, B2O3 can improve resistance to devitrification. However, if the B2O3 content exceeds 35.10%, there is a possibility that the water resistance may deteriorate. On the other hand, if the B2O3 content is 27.00% or less, there is a possibility that the viscosity of the glass melt may increase, and the effect of improving melt permeability may not be fully achieved. Therefore, in the glass of this embodiment, the B2O3 content is set to a range greater than 27.00% and less than 35.10%. From the same viewpoint, the B2O3 content of the glass of this embodiment is preferably 27.50% or more, and more preferably 35.05% or less.

[0043] <al2o3>

[0044] In the glass of this embodiment, Al2O3 is a component that can reduce the thermal expansion coefficient of the glass and improve its water resistance. Furthermore, Al2O3 is a component that can suppress glass phase separation and improve devitrification stability. However, if the Al2O3 content exceeds 12.00%, there is a possibility that the glass's meltability will deteriorate. On the other hand, if the Al2O3 content is less than 6.90%, there is a possibility that the reduction in the glass's thermal expansion coefficient may not be sufficient to achieve the desired improvement in water resistance. Additionally, if the Al2O3 content is less than 6.90%, there is a possibility that glass phase separation cannot be suppressed, and devitrification stability may be significantly reduced. Therefore, in the glass of this embodiment, the Al2O3 content is set to a range of 6.90% or more and 12.00% or less. From the same viewpoint, the Al2O3 content in the glass of this embodiment is preferably 7.00% or more, and more preferably 11.80% or less.

[0045] <li2o>

[0046] In the glass of this embodiment, Li₂O is the component among alkali metal oxides most capable of reducing the viscosity of the glass melt and improving its solubility. However, if the Li₂O content exceeds 8.00%, there is a possibility that the coefficient of thermal expansion of the glass will increase. On the other hand, if the Li₂O content is less than 0.90%, there is a possibility that the effect of reducing the viscosity of the glass melt and improving its solubility may not be sufficiently obtained. Therefore, in the glass of this embodiment, the Li₂O content is set to a range of 0.90% or more and 8.00% or less. From the same viewpoint, the Li₂O content of the glass of this embodiment is preferably 1.00% or more, and more preferably 7.80% or less.

[0047] <na2o>

[0048] In the glass of this embodiment, although Na₂O does not have as significant an effect as Li₂O, it is still a component that reduces the viscosity of the glass melt and improves its solubility. However, if the Na₂O content exceeds 8.10%, the coefficient of thermal expansion increases, and there is also a possibility that the water resistance may significantly deteriorate. On the other hand, if the Na₂O content is less than 0.90%, there is a possibility that the effect of reducing the viscosity of the glass melt and improving its solubility may not be sufficiently obtained. Therefore, in the glass of this embodiment, the Na₂O content is set to be in the range of 0.90% or more and 8.10% or less. From the same viewpoint, the Na₂O content of the glass of this embodiment is preferably 1.00% or more, and more preferably 8.00% or less.

[0049] <k2o>

[0050] In the glass of this embodiment, although K2O does not have as significant an effect as Li2O or Na2O, it is still a component that reduces the viscosity of the glass melt and improves its solubility. However, if the K2O content exceeds 5.10%, there is a possibility that the coefficient of thermal expansion will increase. Therefore, in the glass of this embodiment, the K2O content is set to a range of 0% or more and 5.10% or less. From the same viewpoint, the K2O content of the glass of this embodiment is preferably 5.00% or less.

[0051] <r2o>

[0052] R2O represents the sum of Li2O, Na2O, and K2O. In the glass of this embodiment, the R2O content is 4.00% or more and less than 9.00%. If the R2O content is 9.00% or more, there is a possibility that the thermal expansion coefficient of the glass will increase. On the other hand, if the R2O content is less than 4.00%, there is a possibility that the effect of reducing the viscosity of the glass melt and improving its solubility cannot be sufficiently obtained. From the same point of view, the R2O content of the glass of this embodiment is preferably 4.50% or more, and more preferably 8.97% or less.

[0053] <mgo>

[0054] In the glass of this embodiment, MgO is a component that can improve the durability of the glass. However, if the MgO content exceeds 3.00%, there is a possibility that the meltability of the glass will deteriorate. Therefore, in the glass of this embodiment, the MgO content is set to a range of 0% or more and 3.00% or less. From the same viewpoint, the MgO content of the glass of this embodiment is preferably 2.50% or less.

[0055] <cao>

[0056] In the glass of this embodiment, CaO is a component that can improve the durability of the glass. However, if the CaO content exceeds 3.00%, there is a possibility that the meltability of the glass will deteriorate. Therefore, in the glass of this embodiment, the CaO content is set to a range of 0% or more and 3.00% or less. From the same viewpoint, the CaO content of the optical glass of this embodiment is preferably 2.50% or less.

[0057] <sro>

[0058] In the optical glass of this embodiment, SrO is a component that can improve the glass's anti-devitrification stability and durability. However, if the SrO content exceeds 4.00%, there is a possibility that the glass's meltability will deteriorate. Therefore, in the glass of this embodiment, the SrO content is set to a range of 0% or more and 4.00% or less. From the same viewpoint, the SrO content in the optical glass of this embodiment is preferably 3.50% or less.

[0059] <bao>

[0060] In the glass of this embodiment, BaO is a component that can improve the glass's anti-devitrification stability and durability. However, if the BaO content exceeds 4.00%, there is a possibility that the glass's meltability will deteriorate. Therefore, in the glass of this embodiment, the BaO content is set to a range of 0% or more and 4.00% or less. From the same viewpoint, the BaO content of the optical glass of this embodiment is preferably 3.50% or less.

[0061] <R’O>

[0062] R'O represents the sum of MgO, CaO, SrO, and BaO. In the glass of this embodiment, the R'O content is 0% or more and less than 5.00%. If the R'O content exceeds 5.00%, there is a possibility that the meltability of the glass will deteriorate. Furthermore, from the viewpoint of further improving the durability and anti-devitrification of the glass, the R'O content of the optical glass of this embodiment is preferably 4.50% or less.

[0063] <sb2o3>

[0064] In the glass of this embodiment, Sb₂O₃ is a component capable of degassing the glass melt and can be added arbitrarily. The Sb₂O₃ content is 1.00% or less, which sufficiently achieves the effect of degassing the glass melt. Therefore, in the glass of this embodiment, the Sb₂O₃ content is set to a range of 0% or more and 1.00% or less.

[0065] <f>

[0066] In the glass of this embodiment, fluoride (F) is a clarifying agent. By containing trace amounts (e.g., more than 0.01%) of F in the glass, defoaming is achieved, promoting clarification. On the other hand, if the F content exceeds 1.00%, there is a possibility that harmful fluorine volatiles may be generated and remain in the glass as bubbles. Therefore, in the glass of this embodiment, the F content is set to a range greater than 0.01% and less than 1.00%.

[0067] Here, by using fluorides such as KF, LiF, NaF, MgF2, CaF2, SrF2, BaF2, and AlF3 as raw materials, it is possible to make the glass contain F.

[0068] <cl>

[0069] In the glass of this embodiment, Cl is a refining promoter. Adding 0.05% or more Cl to the glass causes smaller air bubbles to expand and rise, promoting refining. However, if the Cl content exceeds 1.00%, there is a possibility of reducing ultraviolet transmittance. Therefore, in the glass of this embodiment, the Cl content is set to a range of 0.05% or more and 1.00% or less.

[0070] Here, by using chlorides such as KCl, LiCl, NaCl, AlCl3, MgCl2, CaCl2, SrCl2, and BaCl2 as raw materials, it is possible to make the glass contain Cl.

[0071] <Mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3)>

[0072] The glass of this embodiment requires a mass ratio of (R2O+R'O) / (SiO2+B2O3+Al2O3) of less than 0.1. When only the above-mentioned necessary compositional conditions are met, it is possible that both reduced thermal expansion and excellent water resistance cannot be achieved simultaneously. By adjusting the content of components that increase thermal expansion (R2O and R'O) and components that decrease or have no effect on thermal expansion (SiO2, B2O3, and Al2O3), i.e., by using a mass ratio of (R2O+R'O) / (SiO2+B2O3+Al2O3) of less than 0.1, the glass of this embodiment can reliably reduce thermal expansion. Therefore, by meeting the above-mentioned necessary compositional conditions and using a mass ratio of (R2O+R'O) / (SiO2+B2O3+Al2O3) of less than 0.1, the present invention can provide a UV-C transmission glass with good melt flow, low thermal expansion, and excellent water resistance.

[0073] <fe2o3>

[0074] Fe2O3 is a component that can absorb UV-C and reduce its transmittance. However, it is very difficult to completely avoid contamination from glass raw materials and manufacturing processes; generally, glass inevitably contains Fe2O3. Therefore, the glass of this embodiment preferably has a low Fe2O3 content. Specifically, the glass of this embodiment preferably has a Fe2O3 content of 0.01% or less, 0.005% or less, or 0.0005% or less. On the other hand, from the viewpoint of glass productivity, the glass of this embodiment preferably has a Fe2O3 content of 0.00001% or more, or 0.0001% or more.

[0075] <tio2>

[0076] TiO2, like Fe2O3, has the potential to absorb UV-C and reduce its transmittance. However, it is very difficult to completely avoid contamination from glass raw materials and manufacturing processes; generally, glass inevitably contains TiO2. Therefore, the glass of this embodiment preferably has a low TiO2 content. Specifically, the glass of this embodiment preferably has a TiO2 content of 0.02% or less, 0.015% or less, or 0.01% or less. On the other hand, from the viewpoint of glass productivity, the glass of this embodiment preferably has a TiO2 content of 0.0001% or more, or 0.0003% or more.

[0077] <Other Ingredients>

[0078] As long as the objective remains unchanged, the glass of this embodiment can contain components other than those described above (SiO2, B2O3, Al2O3, Li2O, Na2O, K2O, MgO, CaO, SrO, BaO, Sb2O3, F, Cl, Fe2O3, TiO2). Examples of such other components include Gd2O, Y2O3, La2O3, ZrO2, GeO2, Ta2O5, and P2O5. However, from the viewpoint of more reliably producing the desired properties, the content of these other components in the glass of this embodiment is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less. Furthermore, the glass of this embodiment is particularly preferably composed solely of the aforementioned components.

[0079] Here, "consisting solely of the above-mentioned ingredients" includes cases where there are no impurities other than the above-mentioned ingredients, specifically cases where the content of other ingredients is less than 0.2%.

[0080] Cr2O3, NiO, CuO, CeO2, V2O5, WO3, MoO3, MnO2, and CoO are components that may absorb UV-C and reduce its transmittance. Therefore, the glass of this embodiment preferably does not contain these components.

[0081] Next, the various characteristics of the glass in this embodiment will be explained.

[0082] <Meltability>

[0083] In this specification, "meltability" refers to the phenomenon where, by heating a uniformly mixed formulation at a melting temperature, the vitrification reaction proceeds without leaving any unmelted material, resulting in a completely molten state. The glass of this embodiment exhibits good meltability, resulting in a low melting temperature. Furthermore, it is less likely for unmelted material and / or bubbles to remain in the melt. For example, heating the formulation of the glass of this embodiment at a melting temperature of 1450°C in an electric furnace for 3 hours yields a homogeneous glass free of unmelted material and / or bubbles.

[0084] <Ratio of thermal expansion>

[0085] By measuring the mean linear expansion coefficient (α) 100-300℃ The coefficient of linear expansion (CLE) is used to evaluate the rate of thermal expansion. The mean linear expansion coefficient is a property value that expresses the proportion of a body's length change per unit temperature increase, also known as the coefficient of thermal expansion.

[0086] Because the glass of this embodiment has a low coefficient of thermal expansion, it is difficult for the glass to undergo strain and crack thermally when heat is applied to a portion of the glass, causing a large temperature difference within the glass. From the viewpoint of further reducing the coefficient of thermal expansion of the glass, the glass of this embodiment has an average coefficient of linear expansion (α). 100-300℃ The preferred size is 60×10. -7 / ℃ or below. From the same point of view, the average linear expansion coefficient (α) of the glass in this embodiment is below / ℃. 100-300℃ More preferably, it is 59×10 -7 / ℃ or below. Furthermore, the average coefficient of linear expansion (α) of the glass in this embodiment is... 100-300℃ The preferred size is 45×10. -7 / ℃ or higher, more preferably 46×10 -7 / ℃ or above.

[0087] In addition, the aforementioned "average linear expansion coefficient (α)" 100-300℃ ")" refers to the value measured according to the Japan Optical Glass Manufacturers Association standard JOGIS08-2019 "Method for Determination of Thermal Expansion of Optical Glass". Furthermore, for example, by appropriately adjusting the content of each of the above components within a specified range and ensuring that the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is less than 0.1, the "average linear expansion coefficient (α)" of the glass of this embodiment can be measured. 100-300℃ The adjustment of ")".

[0088] <Performance of UV-C Transmission>

[0089] The glass of this embodiment exhibits UV-C transmission performance. The UV-C transmission performance can be evaluated by measuring the internal transmittance at a wavelength of 265 nm within a 1 mm thick glass layer. Specifically, the glass of this embodiment achieves an internal transmittance of 90% or more, and more than 91%, at a wavelength of 265 nm within a 1 mm thick glass layer.

[0090] Furthermore, the aforementioned "internal transmittance" is calculated according to the formula in JOGIS17-2019 "Method for Determining the Internal Transmittance of Optical Glass" of the Japan Optical Glass Manufacturers Association standard. Additionally, the "internal transmittance" of the glass of this embodiment can be adjusted, for example, by appropriately adjusting the content of each of the above components within a specified range.

[0091] Glass transition temperature

[0092] The glass transition temperature of the glass in this embodiment is preferably 510°C or lower. The glass transition temperature represents the temperature at which the melt transforms into glass, and it is also an indicator for determining whether molding is feasible. If the glass transition temperature is high, the molding temperature also becomes high, potentially leading to problems such as the glass sticking to the mold and being difficult to demold. Therefore, the glass transition temperature is preferably as low as possible; in the glass of this embodiment, a glass transition temperature of 500°C or lower is more preferred, and even more preferably 490°C or lower.

[0093] Furthermore, the aforementioned "glass transition temperature" refers to the temperature corresponding to the intersection of two tangents drawn from the low-temperature side and the high-temperature side of the curved portion on the thermal expansion curve measured according to JOGIS 08-2019 "Method for Determination of Thermal Expansion of Optical Glass" of the Japan Optical Glass Manufacturers Association. Additionally, for example, the "glass transition temperature" of the glass of this embodiment can be adjusted by appropriately adjusting the content of each of the above components within a specified range.

[0094] <Water Resistance>

[0095] Water resistance can be evaluated by calculating the weight loss rate. In this specification, for glass, "weight loss rate" refers to the weight loss (mass%) of a 20mm × 10mm × 10mm glass sheet before and after boiling in 1000ml of pure water for 60 minutes. The weight loss rate is calculated using the following formula.

[0096] Weight loss rate = ("mass of the glass slide before boiling treatment" - "mass of the glass slide after boiling treatment") × 100 / "mass of the glass slide before boiling treatment"

[0097] The glass of this embodiment has excellent water resistance; for example, the weight loss rate is preferably less than 0.1% of mass.

[0098] For example, by appropriately adjusting the content of each of the above components within a specified range, the "weight loss rate" of the glass in this embodiment can be adjusted.

[0099] (Manufacturing method of UV-C transmission glass)

[0100] Next, the glass manufacturing method of this embodiment will be described.

[0101] Here, for the glass of this embodiment, as long as the composition (content, mass ratio) of each component meets the above range, there is no particular limitation on its manufacturing method, and it can be manufactured according to conventional manufacturing methods.

[0102] For example, firstly, oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, etc., are weighed according to a prescribed ratio as raw materials for each component that can be included in the optical glass of this embodiment, and the thoroughly mixed raw materials are used as glass preparation raw materials. Next, the glass preparation raw materials are placed in a molten container (e.g., a crucible containing platinum group metals, alloys of platinum group metals, quartz, etc.) that is non-reactive with the glass preparation raw materials, and heated to 1300-1450°C in an electric furnace to melt the raw materials, while stirring as needed. Then, after clarification and homogenization in an electric furnace, the mixture is poured into a mold preheated to an appropriate temperature, and strain is removed by slow cooling in an electric furnace, thereby manufacturing the glass of this embodiment.

[0103] (Applications of UV-C transmission glass)

[0104] The glass used in this embodiment is not particularly limited in its application, but is preferably used for precision molding.

[0105] The glass of this embodiment also has advantages for molding, so by providing the glass of this embodiment to precision molding, the glass parts described later can be easily manufactured.

[0106] (Glass components)

[0107] Hereinafter, a glass component according to one embodiment of the present invention (hereinafter sometimes referred to as "the glass component of this embodiment") will be described.

[0108] The glass component of this embodiment is characterized by using the aforementioned UV-C transmissive glass as a raw material. Because the glass component of this embodiment uses the aforementioned UV-C transmissive glass as a raw material, it exhibits low thermal expansion and excellent water resistance.

[0109] The glass component used in this embodiment is not particularly limited, and examples include LED cover lenses, lens arrays such as microlens arrays, prisms with lens functions, preform materials, and fiber materials. When the glass component includes a lens, the lens can be a spherical lens, an aspherical lens, a plano-concave lens, a plano-convex lens, a biconcave lens, a biconvex lens, a concave meniscus lens, a convex meniscus lens, a microlens, a lens with a diffraction grating, a rod lens, etc. Furthermore, the lens may, as needed, have an antireflection coating or a wavelength-selective partial reflection coating applied to its surface.

[0110] The manufacturing method of the glass component in this embodiment is not particularly limited, and an appropriate known method can be selected according to the purpose. For example, a method for precision molding of the glass in this embodiment can be cited.

[0111] Example

[0112] The present invention will be specifically described below with reference to embodiments and comparative examples, but the present invention is not limited to these embodiments.

[0113] The glass of the embodiments and comparative examples was manufactured by the following method.

[0114] As raw materials for each component listed in Tables 1 to 8, appropriate amounts of oxides, hydroxides, carbonates, nitrates, fluorides, and chlorides were weighed in desired proportions, and the thoroughly mixed raw materials were used as blending materials. Next, the blending materials were placed in a platinum crucible and melted in an electric furnace at a temperature of 1300–1450°C for several hours, while being stirred occasionally with a platinum stirring rod to achieve homogenization and clarify the material. Afterward, the melt was poured into a mold preheated to an appropriate temperature and slowly cooled in an electric furnace to obtain the glass of each example. In each example, AlF3 was used as the fluoride, and NaCl was used as the chloride. Furthermore, the Fe2O3 content of the glass in each example was 0.01% by mass or less, and the TiO2 content was 0.02% by mass or less.

[0115] Furthermore, Comparative Examples 1 and 2 correspond to the compositions of Embodiments 1 and 4 as described in Patent Document 1 (Japanese Patent Application Publication No. 4-342437), respectively. Comparative Example 3 corresponds to Embodiment 1 of Patent Document 2 (Japanese Patent Application Publication No. 2018-197190). Comparative Examples 4, 5, and 6 correspond to Data Nos. 1, 8, and 11 of Patent Document 3 (Japanese Patent Application Publication No. 2012-140314). Comparative Example 7 corresponds to Embodiment 1 of Patent Document 4 (Japanese Patent Application Publication No. 2013-230952).

[0116] For each glass obtained, the following steps were performed to evaluate its melt flow properties, thermal expansion coefficient, water resistance, and UV-C transmission properties (performance in transmitting UV-C), and to determine its glass transition temperature. The results are shown in Tables 1 to 7.

[0117] <Evaluation of Melting Properties>

[0118] As an evaluation of meltability, the raw materials were heated in an electric furnace at 1450°C for 3 hours and then visually evaluated. Cases where no unmelted material or bubbles were identified were designated as "A", and cases where unmelted material or bubbles were identified were designated as "B".

[0119] Evaluation of thermal expansion coefficient

[0120] As an evaluation of thermal expansion rate, the average linear expansion coefficient (α) was measured. 100-300℃ Specifically, the average linear expansion coefficient (α) was measured according to the method described in JOGIS 08-2019 "Method for Determination of Thermal Expansion of Optical Glass" of the Japan Optical Glass Manufacturers Association standard. 100-300℃ The determination of the mean linear expansion coefficient (α) is involved. 100-300℃ The smaller the value of ), the lower the coefficient of thermal expansion (the better).

[0121] <Evaluation of water resistance>

[0122] As an evaluation of water resistance, the weight loss rate was calculated. Specifically, the weight loss rate was calculated using the following method.

[0123] Each example of glass was made into a 20mm × 10mm × 10mm glass slide, which was then boiled in 1000ml of pure water for 60 minutes. The weight loss rate was then calculated using the following formula. A smaller weight loss rate indicates better water resistance.

[0124] Weight loss rate = ("mass of glass slide before boiling treatment" - "mass of glass slide after boiling treatment") × 100 / "mass of glass slide before boiling treatment".

[0125] <Determination of Glass Transition Temperature>

[0126] The glass transition temperature was measured according to the method described in JOGIS 08-2019 "Method for Determination of Thermal Expansion of Optical Glass" of the Japan Optical Glass Manufacturers Association. The lower the glass transition temperature, the better the moldability.

[0127] Evaluation of the performance of UV-C transmission

[0128] To evaluate the performance of UV-C transmission, the internal transmittance at a wavelength of 265 nm within a 1 mm thick glass was measured. Specifically, the internal transmittance at a wavelength of 265 nm within a 1 mm thick glass was calculated according to the method described in JOGIS 17-2019 "Method for Determination of Internal Transmittance of Optical Glass" (Japan Optical Glass Manufacturers Association Standard). A higher internal transmittance value indicates better UV-C transmission performance.

[0129] [Table 1]

[0130] [Table 2]

[0131] [Table 3]

[0132] [Table 4]

[0133] [Table 5]

[0134] [Table 6]

[0135] [Table 7]

[0136] [Table 8]

[0137] According to Tables 1 to 3, for the glasses based on Examples 1 to 20 of the present invention, the evaluation result of meltability is "A", and the average coefficient of linear expansion (α) is... 100-300℃ ) is 60×10 -7 Below ℃, the weight loss is less than 0.10% by mass, and the internal transmittance at a wavelength of 265 nm is above 90% within a 1 mm thick glass. Based on these findings, it is determined that the glasses of Examples 1 to 20 have good melting properties, low thermal expansion coefficient, excellent water resistance, and excellent UV-C transmission performance.

[0138] Furthermore, the glass transition temperature of the glasses in Examples 1-20 is below 510°C. Based on this result, it is determined that the glasses in Examples 1-20 also have advantages for compression molding.

[0139] On the other hand, according to Tables 4 to 8, none of the glasses in Comparative Examples 1 to 33 meet any of the ranges specified in this invention, and therefore become glasses with poor melting properties, high thermal expansion coefficients and / or poor water resistance.

[0140] The meltability evaluation result of the glass in Comparative Example 1 was "B". This is attributed to the high content of SiO2 and the low content of B2O3.

[0141] The glass in Comparative Example 2 was rated as "B" in terms of meltability. This is attributed to the low content of B2O3.

[0142] Furthermore, the internal transmittance [%] of the glasses in Comparative Example 1 and Comparative Example 2 at a wavelength of 265 nm within a glass thickness of 1 mm was low. This is believed to be due to poor meltability of the glasses in Comparative Example 1 and Comparative Example 2, the presence of unmelted material and bubbles in the glass.

[0143] The glass in Comparative Example 3 was rated as "B" for meltability, with an average linear expansion coefficient (α) of [missing value]. 100-300℃ The glass in Comparative Example 3 has a high glass transition temperature. This is attributed to the high content of SiO2 and Na2O, and the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) being 0.1 or higher.

[0144] The average linear expansion coefficient (α) of the glass in Comparative Example 4 100-300℃ The result is high. This is believed to be due to the mass ratio, expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3), being above 0.1.

[0145] The glass in Comparative Example 5 was rated as having "B" for meltability and an average linear expansion coefficient (α). 100-300℃ The glass in Comparative Example 5 has a high glass transition temperature. This is attributed to the high SiO2 content and the mass ratio (R2O+R'O) / (SiO2+B2O3+Al2O3) being 0.1 or higher.

[0146] The average linear expansion coefficient (α) of the glass in Comparative Examples 6 and 7 100-300℃ The result is high. This is believed to be due to the mass ratio, expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3), being above 0.1.

[0147] Although the glass of Comparative Examples 8 to 25 has a mass ratio of (R2O+R'O) / (SiO2+B2O3+Al2O3) of less than 0.1, it is a glass in which the content of any one of the components does not meet the range of the necessary conditions for composition.

[0148] The glass in Comparative Example 8 has a higher weight loss rate. This is attributed to the lower SiO2 content and higher B2O3 content.

[0149] The glass of Comparative Example 9 exhibited a particularly high weight loss rate. Furthermore, phase separation occurred in the glass of Comparative Example 9, with an internal transmittance [%] of almost 0 at a wavelength of 265 nm within a 1 mm thick glass section. This is attributed to the insufficient content of Al₂O₃.

[0150] The glass in Comparative Example 10 had a high weight loss rate. This is attributed to its low Al2O3 content.

[0151] The meltability evaluation results of the glasses in Comparative Examples 11 to 13 were "B". This is attributed to the high content of Al2O3.

[0152] The meltability evaluation result of the glass of Comparative Example 14 was "B". This is believed to be because the glass of Comparative Example 14 does not contain Li2O.

[0153] The meltability evaluation result of the glass of Comparative Example 15 was "B". This is believed to be because the glass of Comparative Example 15 does not contain Li2O and has a low content of Na2O.

[0154] Furthermore, the glass of Comparative Example 15 exhibited a low internal transmittance [%] at a wavelength of 265 nm within a 1 mm glass thickness. This is believed to be due to the poor meltability of the glass in Comparative Example 15, resulting in unmelted material and air bubbles remaining within the glass.

[0155] The average linear expansion coefficient (α) of the glass in Comparative Example 16 100-300℃ The concentration is high, which is attributed to the high K2O content.

[0156] The meltability evaluation result of the glass in Comparative Example 17 was "B". This is attributed to the low R2O content.

[0157] The average linear expansion coefficient (α) of the glass in Comparative Examples 18 and 19 100-300℃ The concentration is high. This is believed to be due to the high content of Li₂O and the low content of Na₂O.

[0158] The average linear expansion coefficient (α) of the glass in Comparative Example 20 100-300℃ The high concentration of Li₂O is attributed to its low content and high content of Na₂O.

[0159] The average linear expansion coefficient (α) of the glass in Comparative Example 21 100-300℃ The high concentration of nitrogen and water has led to a large weight loss rate. This is attributed to the high content of nitrogen, water, and water, which do not contain Li₂O or Na₂O.

[0160] The glass of Comparative Example 22 was rated as "B" in terms of meltability. This is attributed to the high MgO content.

[0161] The glass of Comparative Example 23 was rated as "B" in terms of meltability. This is attributed to its high CaO content.

[0162] The glass of Comparative Example 24 was rated as "B" in terms of meltability. This is attributed to the high SrO content.

[0163] The glass of Comparative Example 25 was rated as "B" in terms of meltability. This is attributed to its high BaO content.

[0164] The average linear expansion coefficient (α) of the glass in Comparative Example 26 100-300℃ The high content of R2O and the large weight loss rate are attributed to the high R2O content and the mass ratio (R2O+R'O) / (SiO2+B2O3+Al2O3) being above 0.1.

[0165] The average linear expansion coefficient (α) of the glass in Comparative Example 32 100-300℃ The high content of R2O is attributed to the high R2O content and the mass ratio (R2O+R'O) / (SiO2+B2O3+Al2O3) being above 0.1.

[0166] Although Comparative Examples 27-31 and 33 meet the necessary compositional conditions, they are glasses with a mass ratio of (R₂O + R'O) / (SiO₂ + B₂O₃ + Al₂O₃) of 0.1 or higher. The average linear expansion coefficient (α) of the glasses in Comparative Examples 27-31... 100-300℃ Both are high. In addition, the glass of Comparative Example 33 has a high weight loss rate. Based on these findings, it is clear that even if the necessary compositional conditions are met, if the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is 0.1 or higher, it is impossible to achieve both reduced thermal expansion and excellent water resistance.

[0167] Industrial applicability

[0168] Based on the present invention, it is possible to provide a UV-C transmission glass with good melting properties, low thermal expansion coefficient and excellent water resistance in a specific composition of aluminoborosilicate glass.

[0169] Furthermore, based on the present invention, it is possible to provide glass components using the aforementioned UV-C transmissive glass. < / cl> < / f> < / bao> < / sro> < / cao> < / mgo>

Claims

1. A UV-C transmission glass, characterized in that, Included by mass% SiO2: 46.90% or more but less than 55.00%; B2O3: greater than 27.00% and less than 35.10%; Al2O3: 6.90% or more and 12.00% or less; Li2O: ≥0.90% and ≤8.00%; Na2O: ≥0.90% and ≤8.10%; K2O: 0% or more and 5.10% or less; R2O: 4.00% or more and less than 9.00%, where R2O represents the sum of Li2O, Na2O and K2O; MgO: ≥0% and ≤3.00%; CaO: 0% or more and 3.00% or less; SrO: 0% or more and 4.00% or less; BaO: 0% or more and 4.00% or less; R'O: 0% or more and less than 5.00%, where R'O represents the sum of MgO, CaO, SrO and BaO; Sb2O3: ≥0% and ≤1.00%; F: Greater than 0.01% and less than 1.00%; Cl: ≥0.05% and ≤1.00%; and The mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is less than 0.

1.

2. The UV-C transmission glass as described in claim 1, wherein, Its average linear expansion coefficient α 100-300℃ 45×10 -7 / ℃ or above and 60×10 -7 / ℃ below.

3. The UV-C transmission glass as described in claim 1 or 2, wherein, The internal transmittance at a wavelength of 265nm within a 1mm thick glass is over 90%.

4. The UV-C transmission glass as described in claim 1 or 2, wherein the glass transition temperature is below 510°C.

5. The UV-C transmission glass as described in claim 1 or 2, wherein, When a glass slide of 20mm×10mm×10mm is boiled in 1000ml of pure water for 60 minutes, the weight loss before and after the boiling treatment is less than 0.1% of the mass.

6. The UV-C transmission glass as described in claim 1 or 2, wherein, The UV-C transmissive glass is used for precision molding.

7. A glass component, characterized in that, The glass component uses the UV-C transmission glass as described in claim 1 or 2 as the raw material.

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