UV-transmitting glass

Abstract

Provided is ultraviolet transmission glass having not only high transmittance in a deep ultraviolet range but also high weather resistance. The ultraviolet transmission glass according to the present invention is characterized by having a glass composition containing, in mass%, 55-80% of SiO2, 1-25% of Al2O3, 10.8-30% of B2O3, 0-10% of Na2O, less than 0-1.6% of K2O, 0.1-10% of Li2O+Na2O+K2O, 0-5% of BaO, and 0-1% of Cl, and has a thickness of 0.5 mm and an external transmittance of 38% or more at a wavelength of 200 nm.

Description

[Technical Field]

[0001] This invention relates to ultraviolet-transmitting glass. [Background technology]

[0002] Currently, light sources with high output in the deep ultraviolet region (for example, wavelength range 200-350 nm) have been developed and are used in ultraviolet lamps, magnetic recording media writing devices, etc. These light sources utilize ultraviolet-transmitting glass with high transmittance in the deep ultraviolet region (for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2016 / 194780 [Patent Document 2] Patent No. 5847998 [Overview of the project] [Problems that the invention aims to solve]

[0004] The higher the transmittance of the UV-transmitting glass in the deep ultraviolet region, the better the performance of the light source. For example, using such UV-transmitting glass in the outer casing of a UV lamp for sterilization purposes can provide higher sterilization power.

[0005] However, conventional UV-transmitting glass often uses glass compositions with a high boron oxide content to increase transmittance in the deep ultraviolet region. Compared to common borosilicate glass (Pyrex glass) or soda-lime glass, this results in lower weather resistance and a shorter product lifespan for electronic devices using it.

[0006] This invention was made in view of the above circumstances, and its technical objective is to create an ultraviolet-transmitting glass that has high transmittance in the deep ultraviolet region and also high weather resistance. [Means for solving the problem]

[0007] As a result of intensive studies, the inventors have found that the above technical problems can be solved by regulating the glass composition and glass properties within a predetermined range, and propose the present invention. That is, the ultraviolet-transmitting glass of the present invention contains, as a glass composition, in mass %, 55 to 80% of SiO2, 1 to 25% of Al2O3, 10.8 to 30% of B2O3, 0 to 10% of Na2O, less than 0 to 1.6% of K2O, 0.1 to 10% of Li2O + Na2O + K2O, 0 to 5% of BaO, and 0 to 1% of Cl, and is characterized in that the external transmittance at a thickness of 0.5 mm and a wavelength of 200 nm is 38% or more. Here, the "external transmittance at a thickness of 0.5 mm and a wavelength of 200 nm" can be measured with a commercially available spectrophotometer (for example, V-670 manufactured by JASCO Corporation) using a measurement sample polished on both sides to an optical polishing surface (mirror surface).

[0008] Further, the ultraviolet-transmitting glass of the present invention preferably contains, as a glass composition, in mass %, 65 to 74% of SiO2, 3.5 to 20% of Al2O3, 11.5 to 25% of B2O3, 0.1 to 8% of Na2O, 0 to 1% of K2O, 1 to 10% of Li2O + Na2O + K2O, 0 to 1.9% of BaO, 0.01 to 0.5% of Cl, and 0.00001 to 0.00200% of Fe2O3 + TiO2.

[0009] Further, when the ultraviolet-transmitting glass of the present invention is subjected to a high-speed accelerated life test (HAST) at a temperature of 121°C, a relative humidity of 85%, and a test time of 24 hours, it is preferable that the maximum long side of foreign substances generated on the glass surface is 100 μm or less. Here, the "high-speed accelerated life test (HAST)" can be tested using, for example, a commercially available device (for example, manufactured by Hirayama Seisakusho). The "maximum long side of foreign substances" can be observed using, for example, a digital microscope manufactured by Keyence Corporation.

[0010] In addition, the ultraviolet - transmitting glass of the present invention preferably has a temperature corresponding to a glass viscosity of Logρ = 6.0 dPa·s of 870°C or lower. Here, the "temperature corresponding to a glass viscosity of Logρ = 6.0 dPa·s" is obtained by fitting the glass viscosity to Fulcher's equation after measuring the strain point, annealing point, softening point, temperature corresponding to a glass viscosity of Logρ = 4.0 dPa·s, temperature corresponding to a glass viscosity of Logρ = 3.0 dPa·s, and temperature corresponding to a glass viscosity of Logρ = 2.5 dPa·s using the platinum ball pulling - up method, and then calculating the temperature corresponding to a glass viscosity of Logρ = 6.0 dPa·s.

[0011] In addition, the ultraviolet - transmitting glass of the present invention preferably has a temperature corresponding to a glass viscosity of Logρ = 4.0 dPa·s of 1200°C or lower. Here, the "temperature corresponding to a glass viscosity of Logρ = 4.0 dPa·s" can be measured by the platinum ball pulling - up method.

[0012] In addition, the ultraviolet - transmitting glass of the present invention preferably has an average thermal expansion coefficient at 30 - 380°C of 40×10 -7 ~65×10 -7 / °C. Here, the "average thermal expansion coefficient at 30 - 380°C" can be measured with a commercially available dilatometer.

[0013] In addition, the ultraviolet - transmitting glass of the present invention preferably has an external transmittance of 70% or more at a thickness of 0.5 mm and a wavelength of 230 nm. Here, the "external transmittance at a thickness of 0.5 mm and a wavelength of 230 nm" can be measured with a commercially available spectrophotometer (for example, V - 670 manufactured by JASCO Corporation) using a measurement sample polished on both sides to an optical polishing surface (mirror surface).

[0014] In addition, for the ultraviolet - transmitting glass of the present invention, when the external transmittance (%) at a thickness of 0.5 mm and a wavelength of 200 nm is T 200 and the external transmittance (%) at a thickness of 0.5 mm and a wavelength of 260 nm is T 260 , then T 200 / T 260It is preferable that the relationship ≥0.45 is satisfied. Here, the "external transmittance at a thickness of 0.5 mm and a wavelength of 260 nm" can be measured using a commercially available spectrophotometer (for example, JASCO V-670) with both sides polished to an optically polished surface (mirror surface) as the measurement sample.

[0015] Furthermore, it is preferable that the ultraviolet-transmitting glass of the present invention has a functional film formed on its surface.

[0016] Furthermore, it is preferable that the ultraviolet-transmitting glass of the present invention has a lens structure formed on its surface.

[0017] Furthermore, it is preferable that the ultraviolet-transmitting glass of the present invention has a prism structure formed on its glass surface.

[0018] Furthermore, it is preferable that the ultraviolet-transmitting glass of the present invention has an adhesive layer formed on its surface.

[0019] Furthermore, the ultraviolet-transmitting glass of the present invention is preferably plate-shaped or tubular in shape, and has a thickness of 0.1 to 3.0 mm.

[0020] Furthermore, the ultraviolet-transmitting glass of the present invention is preferably tubular in shape and has an inner diameter of 1 mm or more.

[0021] Furthermore, the ultraviolet-transmitting glass of the present invention is preferably used in any of the following: ultraviolet light-emitting diodes (LEDs), semiconductor packages, photodetector encapsulation packages, ultraviolet light-emitting lamps, or photomultiplier tubes. [Brief explanation of the drawing]

[0022] [Figure 1] This is the transmittance curve for sample No. 13 in the Examples section, with a wavelength range of 200-400 nm and a thickness of 0.5 mm. [Modes for carrying out the invention]

[0023] The ultraviolet-transmitting glass of the present invention contains, by mass%, SiO2 55-80%, Al2O3 1-25%, B2O3 10.8-30%, Na2O 0-10%, K2O 0-1.6%, Li2O+Na2O+K2O 0.1-10%, BaO 0-5%, and Cl 0-1%. The reasons for limiting the content of each component as described above are explained below. In the description of the content of each component, percentages represent mass% unless otherwise specified.

[0024] SiO2 is the main component that forms the framework of glass. The SiO2 content is preferably 55-80%, 60-78%, 62-75%, 65-74%, and particularly 66-72%. If the SiO2 content is too low, the Young's modulus, acid resistance, and weather resistance tend to decrease. On the other hand, if the SiO2 content is too high, the high-temperature viscosity increases, the meltability tends to decrease, and devitrified crystals such as cristobalite tend to precipitate, causing the liquidus temperature to rise. If the SiO2 content is outside the above range, the glass tends to split into phases, and the weather resistance tends to decrease.

[0025] Al2O3 is a component that enhances weather resistance and Young's modulus, as well as suppressing phase separation and devitrification. The Al2O3 content is preferably 1-25%, 2-20%, 3.5-10%, 4-7%, and particularly 4.5-6.5%. Other preferred ranges are 1-25%, 3-19%, 3.5-15%, 4-12%, 4.3-10%, 5-9%, 6.5-8.8%, 7-8.6%, and particularly 7.5-8.5%. Within this range, transmittance and weather resistance are improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. If the Al2O3 content is too low, weather resistance and Young's modulus tend to decrease, and the glass is more prone to phase separation and devitrification. On the other hand, if the Al2O3 content is too high, the high-temperature viscosity increases, and meltability tends to decrease.

[0026] B2O3 is a component that enhances meltability, devitrification resistance, and transmittance in the deep ultraviolet region, as well as improving scratch resistance and increasing strength. The B2O3 content is preferably 10.8-30%, 11.5-25%, 13-24%, 14-23%, 15-22%, 15.5-21%, 15.8-20%, 16-19%, and especially 16.1-18.1%. If the B2O3 content is too low, it becomes difficult to enjoy the above effects. On the other hand, if the B2O3 content is too high, Young's modulus, acid resistance, and weather resistance tend to decrease. Also, the glass tends to dephaseize, and weather resistance tends to decrease.

[0027] Al2O3 and B2O3 are components that enhance devitrification resistance. The combined amount of Al2O3 and B2O3 is preferably 15-30%, 16-28%, 17-27%, and particularly 19-26%. Other preferred ranges are 15-30%, 18-28.5%, 22-27.5%, and particularly 25-26.5%. Within this range, transmittance and weather resistance are improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. If the Al2O3+B2O3 content is too low, the glass will devitrify easily. On the other hand, if the combined amount of Al2O3 and B2O3 is too high, the balance of components in the glass composition is disrupted, and the glass will conversely become more prone to devitrification.

[0028] The B2O3-Al2O3 content is preferably 10-20%, 11-19%, 12-17%, and particularly 13-16%. Other preferred ranges are 5-15%, 6-13%, 7-12%, and particularly 8-9.9%. Within this range, transmittance and weather resistance are improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. If the B2O3-Al2O3 content is too low, transmittance in the deep ultraviolet region tends to decrease. On the other hand, if the B2O3-Al2O3 content is too high, weather resistance decreases, and the glass becomes more prone to phase separation. Note that "B2O3-Al2O3" is the value obtained by subtracting the Al2O3 content from the B2O3 content.

[0029] Li2O is a component that lowers high-temperature viscosity, significantly increases meltability, and contributes to the initial melting of glass raw materials. The preferred Li2O content is 0-5%, 0.1-3%, 0.2-2%, 0.5-1.9%, 0.6-1.6%, and particularly 0.7-1.2%. Other preferred ranges are 0-5%, 0.3-4%, 0.8-3.5%, and particularly 2-3%. Within this range, transmittance and weather resistance are improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. If the Li2O content is too low, meltability tends to decrease, and the coefficient of thermal expansion may become unduly low. On the other hand, if the Li2O content is too high, the glass tends to separate into phases. It also increases the batch cost of the glass. Furthermore, weather resistance tends to decrease.

[0030] Na2O is a component that lowers high-temperature viscosity, significantly increases meltability, and contributes to the initial melting of glass raw materials. It is also a component for adjusting the coefficient of thermal expansion. The preferred Na2O content is 0-10%, 0.1-8%, 0.5-7%, 0.7-6.5%, 0.8-6.2%, 0.9-6%, 1-5.8%, 1.5-5.5%, 2-5.4%, 3-5.3%, 3.8-5.1%, and particularly 4-5%. Other preferred ranges are 0-10%, 0.2-8.5%, 0.6-7.5%, 1.8-3.9%, and particularly 2-3%. Within this range, transmittance and weather resistance are improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. If the Na2O content is too low, meltability tends to decrease, and there is a risk that the coefficient of thermal expansion will become unduly low. On the other hand, if the Na2O content is too high, the coefficient of thermal expansion may become unduly high. Furthermore, weather resistance may be easily reduced.

[0031] K2O is a component that lowers high-temperature viscosity, significantly improves meltability, and contributes to the initial melting of glass raw materials. It is also a component that adjusts the coefficient of thermal expansion. The K2O content is preferably 0-1.6%, 0.1-1.5%, and particularly 0.5-1%. Other preferred ranges are 0-1.6%, 0-0.9%, 0-0.7%, 0-0.4%, and particularly 0-0.1%. Within this range, transmittance and weather resistance are improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. If the K2O content is too high, there is a risk of unreasonably high batch costs. Furthermore, the glass may dephase, and its weather resistance may decrease.

[0032] Li2O, Na2O, and K2O are alkali metal oxide components that reduce high-temperature viscosity, significantly improve meltability, and contribute to the initial melting of glass raw materials. The content of Li2O+Na2O+K2O (total amount of Li2O, Na2O, and K2O) is preferably 0.1-10%, 0.1-9.5%, 0.1-9.2%, 0.1-9.0%, 0.2-8.8%, 0.5-8.5%, 0.8-8.2%, 1.0-8.0%, 2-7.8%, 3-7.6%, 3.5-7.2%, and particularly 4-7%. If the content of Li2O+Na2O+K2O is too low, meltability tends to decrease. On the other hand, if the content of Li2O+Na2O+K2O is too high, weather resistance tends to decrease, and there is a risk that the coefficient of thermal expansion will become unduly high.

[0033] If the mass ratio Li2O / (Li2O+Na2O+K2O) is too small, the meltability tends to decrease, and there is a risk that the coefficient of thermal expansion will become unduly low. On the other hand, if the mass ratio Li2O / (Li2O+Na2O+K2O) is too large, the glass tends to separate into phases. Also, the batch cost of the glass increases. Therefore, the mass ratio Li2O / (Li2O+Na2O+K2O) is preferably 0~0.50, 0.01~0.40, 0.02~0.30, 0.03~0.20, and especially 0.04~0.19. Note that "Li2O / (Li2O+Na2O+K2O)" refers to the value obtained by dividing the Li2O content by the total amount of Li2O, Na2O, and K2O.

[0034] If the mass ratio Na2O / (Li2O+Na2O+K2O) is too small, the meltability tends to decrease. On the other hand, if the mass ratio Na2O / (Li2O+Na2O+K2O) is too large, the electrical resistivity during glass melting increases, which may cause the glass to electrolyze and generate bubbles. Therefore, the mass ratio Na2O / (Li2O+Na2O+K2O) is preferably 0.10~1.00, 0.13~0.90, 0.15~0.85, 0.20~0.80, 0.25~0.78, and especially 0.33~0.70. Note that "Na2O / (Li2O+Na2O+K2O)" refers to the value obtained by dividing the Na2O content by the total amount of Li2O, Na2O, and K2O.

[0035] If the mass ratio K2O / (Li2O+Na2O+K2O) is too high, the batch cost of the glass will increase. Therefore, the mass ratio K2O / (Li2O+Na2O+K2O) is preferably 0-0.80, 0-0.75, 0-0.70, 0.01-0.60, 0.03-0.50, and especially 0.04-0.40. Other preferred ranges are 0-0.80, 0-0.65, 0-0.55, 0-0.45, 0-0.25, and especially 0-0.10. Within this range, transmittance and weather resistance are improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. Note that "K2O / (Li2O+Na2O+K2O)" refers to the value obtained by dividing the K2O content by the total amount of Li2O, Na2O, and K2O.

[0036] BaO is a component that enhances devitrification resistance. Too much BaO makes the glass more prone to phase separation. The BaO content is preferably 0-5%, 0.1-3%, 0.5-2%, and 1-1.9%. Other preferred ranges are 0-5%, 0-4%, 0-2.5%, 0-1.5%, 0-0.4%, and especially 0-0.1%. Within this range, transmittance is improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost.

[0037] Cl is a component that acts as a clarifying agent. The preferred Cl content is 0-1%, 0.01-0.9%, 0.02-0.5%, 0.03-0.2%, 0.04-0.15%, 0.05-0.10%, 0.06-0.09%, and 0.07-0.08%. If the Cl content is too low, the clarifying effect will be diminished. On the other hand, if the Cl content is too high, the clarifying gas may remain in the glass as bubbles.

[0038] In addition to the components mentioned above, other components may be introduced as long as they do not significantly reduce the transmittance in the deep ultraviolet region. From the viewpoint of effectively enjoying the effects of the present invention, the content of components other than those mentioned above is preferably 10% or less, 7% or less, and particularly 5% or less in total.

[0039] P2O5 is a component that enhances glass-forming ability. If the P2O5 content is too low, the glass may become unstable and its resistance to devitrification may decrease. On the other hand, if the P2O5 content is too high, the glass may split into phases, and its weather resistance and water resistance may decrease. Therefore, the P2O5 content is preferably 0-5%, 0.1-4%, 0.3-3%, 0.5-2%, and especially 1-1.5%.

[0040] MgO is a component that lowers high-temperature viscosity and increases meltability, and among alkaline earth metal oxides, it is a component that significantly increases Young's modulus. However, if the MgO content is too high, the glass becomes prone to phase separation and devitrification. Therefore, the MgO content is preferably 0-3%, 0-2%, 0-1%, and especially 0.1-0.9%. Other preferred ranges are 0-3%, 0-2.5%, 0-1.5%, 0-0.4%, and especially 0-0.1%. Within this range, the transmittance is improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost.

[0041] CaO is a component that lowers high-temperature viscosity and increases meltability. Furthermore, among alkaline earth metal oxides, its raw material is relatively inexpensive, thus reducing raw material costs. However, if the CaO content is too high, the glass tends to dephase, leading to a decrease in weather resistance. Therefore, the CaO content is preferably 0-3%, 0-1%, 0.01-0.8%, and 0.1-0.5%. Other preferred ranges are 0-3%, 0-2.5%, 0-1.5%, 0-0.4%, and especially 0-0.1%. Within this range, transmittance is improved, and the glass viscosity can be easily adjusted to a level that allows for low-cost production.

[0042] SrO is a component that enhances resistance to devitrification. However, if the SrO content is too high, the glass becomes more prone to phase separation. The preferred SrO content is 0-3%, 0-2%, 0-1%, and particularly 0.1-0.5%. Other preferred ranges are 0-3%, 0-2.5%, 0-1.5%, 0-0.4%, and particularly 0-0.1%. Within this range, transmittance is improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost.

[0043] MgO, CaO, SrO, and BaO are components that lower high-temperature viscosity and increase meltability. However, if the content of MgO+CaO+SrO+BaO is too high, the glass becomes prone to devitrification and phase separation. Therefore, the content of MgO+CaO+SrO+BaO (total amount of MgO, CaO, SrO, and BaO) is preferably 0-5%, 0.1-3%, and particularly 0.5-2%. Other preferred ranges are 0-5%, 0-4%, 0-3%, 0-2.5%, 0-1.5%, 0-0.4%, and particularly 0-0.1%. Within this range, transmittance is improved and it becomes easier to adjust the glass viscosity to one that can be produced at low cost.

[0044] If the mass ratio (MgO+CaO+SrO+BaO) / Al2O3 is too small, the resistance to devitrification decreases, making it difficult to form into plates or tubes. On the other hand, if the mass ratio (MgO+CaO+SrO+BaO) / Al2O3 is too large, the glass is more prone to phase separation. There is also a risk that the density and thermal expansion coefficient will increase unduly. Therefore, the mass ratio (MgO+CaO+SrO+BaO) / Al2O3 is preferably 0-1, 0.1-0.95, 0.2-0.90, 0.3-0.80, 0.4-0.70, and particularly 0.41-0.66. Other preferred ranges are 0-1, 0-0.5, 0-0.4, 0-0.3, 0-0.2, and particularly 0-0.1. Within this range, the transmittance is improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. Note that "(MgO+CaO+SrO+BaO) / Al2O3" refers to the value obtained by dividing the total amount of MgO, CaO, SrO, and BaO by the amount of Al2O3.

[0045] If the B2O3-(MgO+CaO+SrO+BaO) content is too low, the transmittance in the deep ultraviolet region will decrease, and the density will tend to increase. On the other hand, if the B2O3-(MgO+CaO+SrO+BaO) content is too high, the weather resistance will tend to decrease. Therefore, the B2O3-(MgO+CaO+SrO+BaO) content is preferably 10-20%, 11-19%, 12-18%, 13-17%, and especially 14-16%. Other preferred ranges are 10-20%, 12-19.9%, 14-19.7%, 16-19.4%, and especially 17-19%. Within this range, transmittance is improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. Note that "B2O3-(MgO+CaO+SrO+BaO)" refers to the value obtained by subtracting the combined amounts of MgO, CaO, SrO, and BaO from the B2O3 content.

[0046] If the mass ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3) is too small, the high-temperature viscosity increases, leading to a higher melting temperature, which tends to increase the manufacturing cost of glass plates or glass tubes. On the other hand, if the mass ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3) is too large, the transmittance in the deep ultraviolet region tends to decrease. Therefore, the mass ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3) is preferably 0-0.1, 0.001-0.09, 0.002-0.08, 0.003-0.08, 0.004-0.0.07, 0.005-0.06, 0.007-0.05, 0.008-0.04, 0.009-0.03, and particularly 0.01-0.02. Other preferred ranges are 0-0.1, 0-0.09, 0-0.08, 0-0.0.07, 0-0.06, 0-0.05, 0-0.04, 0-0.03, and particularly 0-0.01. Within this range, the transmittance is improved, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost. Note that "(mass ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3))" refers to the value obtained by dividing the total amount of MgO, CaO, SrO, and BaO by the total amount of SiO2, Al2O3, and B2O3.

[0047] ZrO2 is a component that enhances weather resistance and acid resistance, but if it is included in large quantities in the glass composition, the glass becomes prone to devitrification. Therefore, the ZrO2 content is preferably 0-0.1%, 0.001-0.02%, and particularly 0.0001-0.01%.

[0048] ZnO is a component that reduces high-temperature viscosity without decreasing low-temperature viscosity. It also enhances weather resistance. On the other hand, if the ZnO content is too high, the glass tends to split into phases, its devitrification resistance decreases, and its density increases. The preferred ZnO content is 0-5%, 0.1-4%, 0.3-3%, 0.5-2.9%, 0.7-2.8%, and particularly 1.3-2.4%. Other preferred ranges are 0-5%, 0-4.5%, 0-3.5%, 0-2.5%, 0-1.5%, 0-0.3%, and particularly 0-0.1%. Within this range, transmittance improves, and it becomes easier to adjust the glass viscosity to one that can be produced at low cost.

[0049] Fe2O3 is a component that reduces the transmittance in the deep ultraviolet region. The content of Fe2O3 is preferably 0.0010% (10 ppm) or less, 0.00001 - 0.0008% (0.1 - 8 ppm), 0.00001 - 0.0006% (0.1 - 6 ppm). "Fe2O3" includes both trivalent iron oxide and divalent iron oxide, and the divalent iron oxide shall be treated after conversion to trivalent iron oxide. Other polyvalent oxides shall be treated similarly based on the indicated oxides.

[0050] Fe ions in iron oxide are in the state of Fe 2+ or Fe 3+ . When the proportion of Fe 2+ is too small, the transmittance in the deep ultraviolet region tends to decrease. Therefore, the mass ratio of Fe 2+ / (Fe 2+ +Fe 3+ ) in the iron oxide contained in the ultraviolet-transmitting glass of the present invention is preferably 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, particularly 0.5 or more.

[0051] TiO2 is a component that reduces the transmittance in the deep ultraviolet region. The content of TiO2 is preferably 0.0010% (10 ppm) or less, 0.00030% (3 ppm) or less, 0.00001 - 0.00015% (0.1 - 1.5 ppm). When the content of TiO2 is too large, the glass is colored and the transmittance in the deep ultraviolet region tends to decrease.

[0052] The total content of Fe2O3 and TiO2 is preferably 0.0020% (20 ppm) or less, 0.0010% (10 ppm) or less, particularly 0.00001 - 0.0007% (0.1 - 7 ppm). When the total content of Fe2O3 and TiO2 is too large, the glass is colored and the transmittance in the deep ultraviolet region tends to decrease.

[0053] F is a component that acts as a clarifying agent and is a component that reduces viscosity and enhances meltability. The content of F is preferably 0 - 3%, 0 - 2%, 0.1 - 1.5%, 0.5 - 1.5%.

[0054] Sb2O3 is a component that acts as a clarifying agent. The Sb2O3 content is preferably 0.1% or less, 0.08% or less, 0.06% or less, 0.04% or less, 0.02% or less, 0.01% or less, and especially less than 0.005%. If the Sb2O3 content is too high, the transmittance in the deep ultraviolet region tends to decrease.

[0055] SnO2 is a component that acts as a clarifying agent. The SnO2 content is preferably 0.2% or less, 0.17% or less, 0.14% or less, 0.11% or less, 0.08% or less, 0.05% or less, 0.02% or less, 0.01% or less, 0.005% or less, and especially less than 0.005%. If the SnO2 content is too high, the transmittance in the deep ultraviolet region tends to decrease.

[0056] F, Cl, and SnO2 are components that act as clarifying agents. The content of F+Cl+SnO2 (total amount of F, Cl, and SnO2) is preferably 10-30,000 ppm (0.001-3%), 50-20,000 ppm, 100-10,000 ppm, 250-5,000 ppm, 500-3,000 ppm, and especially 700-2,000 ppm. If the content of F+Cl+SnO2 is too low, it will be difficult to achieve a clarifying effect. On the other hand, if the content of F+Cl+SnO2 is too high, the clarifying gas may remain in the glass as bubbles.

[0057] The ultraviolet-transmitting glass of the present invention preferably has the following glass properties.

[0058] In the ultraviolet-transmitting glass of the present invention, the longest side of foreign matter generated on the glass surface after a fast-accelerated lifetime test (HAST) at a temperature of 121°C, relative humidity of 85%, and test duration of 24 hours is preferably 100 μm or less, 80 μm or less, 60 μm or less, 40 μm or less, and particularly 20 μm or less. If large foreign matter is generated on the glass surface after the fast-accelerated lifetime test, the transmittance in the deep ultraviolet region decreases, shortening the product life of the electronic device.

[0059] The temperature corresponding to the glass viscosity Logρ = 6.0 dPa·s is preferably 870°C or lower, 860°C or lower, 855°C or lower, 850°C or lower, 840°C or lower, and particularly 835°C or lower. The temperature corresponding to the glass viscosity Logρ = 6.0 dPa·s is suitable for softening the ultraviolet-transmitting glass and sealing it with other materials (for example, a diode sealed inside the glass tube). If this temperature is too high, the electronic components sealed inside will deteriorate and will have difficulty performing their function.

[0060] The temperature corresponding to the glass viscosity Logρ = 4.0 dPa·s is preferably 1200°C or lower, 1180°C or lower, 1150°C or lower, 1120°C or lower, 1100°C or lower, 1080°C or lower, 1060°C or lower, and particularly 1040°C or lower. The temperature corresponding to the glass viscosity Logρ = 4.0 dPa·s is suitable for sealing one end of the glass tube. If this temperature is too high, the energy required to heat the glass tube increases, leading to higher manufacturing costs.

[0061] The average coefficient of thermal expansion at 30-380°C is preferably 40 × 10⁻⁶. -7 ~65×10 -7 / ℃, 41×10 -7 ~64×10 -7 / ℃, 42×10 -7 ~62×10 -7 / ℃, 43×10 -7 ~60×10 -7 / ℃, 44×10 -7 ~58×10 -7 / ℃, 45×10 -7 ~55×10 -7 / ℃, especially 46 × 10 -7 ~52×10 -7 The temperature is / °C. If the average coefficient of thermal expansion between 30 and 380°C is too low, when sealing with other materials (for example, a diode sealed inside the glass tube), strain may occur at the interface between the two materials due to the difference in thermal expansion coefficients, potentially causing the glass to break. On the other hand, if the average coefficient of thermal expansion between 30 and 380°C is too high, when heat processing the glass, there is a risk of the glass breaking due to thermal shock, etc.

[0062] The external transmittance at a thickness of 0.5 mm and a wavelength of 200 nm is preferably 38% or higher, 40% or higher, 45% or higher, 50% or higher, 55% or higher, 57% or higher, 59% or higher, and particularly 60% or higher. If the external transmittance at a thickness of 0.5 mm and a wavelength of 200 nm is too low, deep ultraviolet light will not pass through easily, and the performance of the mounted light source and electronic devices will likely deteriorate.

[0063] The external transmittance at a thickness of 0.5 mm and a wavelength of 230 nm is preferably 70% or higher, 73% or higher, 74% or higher, and particularly 75% or higher. If the external transmittance at a thickness of 0.5 mm and a wavelength of 230 nm is too low, deep ultraviolet light will not pass through easily, and the performance of the mounted light source and electronic devices will likely deteriorate.

[0064] The external transmittance at a thickness of 0.5 mm and a wavelength of 260 nm is preferably 80% or higher, 82% or higher, and particularly 83% or higher. If the external transmittance at a thickness of 0.5 mm and a wavelength of 260 nm is too low, deep ultraviolet light will not pass through easily, and the performance of the mounted light source and electronic devices will likely deteriorate.

[0065] External transmittance (%) at a thickness of 0.5 mm and a wavelength of 200 nm is T 200 The external transmittance (%) at a thickness of 0.5 mm and a wavelength of 260 nm is T 260 In that case, T 200 / T 260 It is preferable that the relationship ≥ 0.45 is satisfied, T 200 / T 260 It is more preferable that the relationship ≥ 0.50 is satisfied, T 200 / T 260 It is even more preferable that the relationship ≥ 0.55 is satisfied, T 200 / T 260 It is even more preferable that the relationship ≥ 0.60 is satisfied, T 200 / T 260 It is particularly preferable that the relationship ≥ 0.65 is satisfied. 200 / T 260 If the value is too small, deep ultraviolet light will not penetrate easily, which can easily degrade the performance of the light source and electronic devices installed.

[0066] The strain point is preferably 400°C or higher, 410°C or higher, and particularly 415°C or higher. If the strain point is too low, unintended deformation of the glass is likely to occur when a functional film is deposited on the glass surface at high temperatures.

[0067] The softening point is preferably 850°C or lower, 800°C or lower, 750°C or lower, and especially 700°C or lower. If the softening point is too high, the load on the glass melting furnace increases, which tends to drive up the cost of glass production.

[0068] The temperature at which the glass viscosity Logρ = 2.5 dPa·s is preferably 1630°C or lower, 1600°C or lower, 1560°C or lower, 1540°C or lower, 1520°C or lower, 1500°C or lower, and especially 1480°C or lower. If the temperature at which the glass viscosity Logρ = 2.5 dPa·s is too high, the meltability decreases, which tends to increase the cost of glass manufacturing.

[0069] The liquidus temperature is preferably 1050°C or lower, 1000°C or lower, 950°C or lower, 900°C or lower, and particularly 850°C or lower. The glass viscosity at the liquidus temperature is preferably 4.0 dPa·s or higher, 4.3 dPa·s or higher, 4.5 dPa·s or higher, 4.8 dPa·s or higher, 5.1 dPa·s or higher, 5.3 dPa·s or higher, and particularly 5.5 dPa·s or higher, as measured by Logρ. If the liquidus temperature is too high, the devitrification resistance decreases, making it difficult to mold into the desired shape. Also, if the glass viscosity at the liquidus temperature is too low, the devitrification resistance decreases, making it difficult to mold into the desired shape.

[0070] The ultraviolet-transmitting glass of the present invention preferably has a functional film formed on its surface, such as an anti-reflective film, a reflective film, a high-pass filter, a low-pass filter, or a band-pass filter. Furthermore, to further enhance weather resistance, it is also preferable to form a silica film or the like on the glass surface.

[0071] The ultraviolet-transmitting glass of the present invention preferably also has a lens structure formed on its surface. By forming a lens structure, such as a concave lens, convex lens, Fresnel lens, or lens array, on the glass surface, it becomes possible to focus and scatter deep ultraviolet light.

[0072] The ultraviolet-transmitting glass of the present invention preferably also has a prism structure formed on its surface. Forming a prism structure on the glass surface makes it possible to refract deep ultraviolet light.

[0073] The ultraviolet-transmitting glass of the present invention can be used in semiconductor packages. In this case, it is preferable that an adhesive layer is formed on the glass surface. As the adhesive layer, organic substances, inorganic substances, or mixtures thereof can be used. For example, ultraviolet-curing adhesives and gold-tin solder can be used. In addition, inorganic fillers may be added to the ultraviolet-curing adhesive to increase the strength of the adhesive layer.

[0074] The shape of the ultraviolet-transmitting glass of the present invention is not particularly limited and can be, for example, flat, curved, straight, curved, rod-shaped, spherical, container-shaped, block-shaped, etc.

[0075] When the shape is flat, the dimensions of the main surface are preferably 100mm x 100mm or larger, 200mm x 200mm or larger, 400mm x 400mm or larger, 1000mm x 1000mm or larger, and especially 2000mm x 2000mm or larger. The larger the dimensions of the main surface, the more small glass plates can be obtained, making it easier to reduce the manufacturing cost of electronic devices.

[0076] If the shape is tubular, the inner diameter is preferably 1 mm or more, 1.3 mm or more, 1.5 mm or more, 2 mm or more, 2.5 mm or more, 3 mm or more, 3.5 mm or more, 5 mm or more, 10 mm or more, 20 mm or more, 25 mm or more, and especially 30 to 200 mm. The larger the inner diameter, the easier it is to seal electronic components inside the glass tube, for example, to seal filaments and switches.

[0077] In the ultraviolet-transmitting glass of the present invention, the thickness is preferably 0.1 to 3.0 mm, 0.2 to 1.0 mm, or 0.3 to 0.6 mm. Although the transmittance in the deep ultraviolet region decreases as the thickness increases, the ultraviolet-transmitting glass of the present invention has high transmittance in the deep ultraviolet region, so it is possible to ensure high transmittance even with a greater thickness than conventional products.

[0078] The surface roughness Ra of the glass surface is preferably 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, and especially 1 nm or less. If the surface roughness Ra of the glass surface is too high, the transmittance in deep ultraviolet light tends to decrease.

[0079] The ultraviolet-transmitting glass of the present invention is preferably used in any of the following: ultraviolet light-emitting diodes (LEDs), semiconductor packages, photodetector encapsulation packages, ultraviolet light-emitting lamps, and photomultiplier tubes. As semiconductor photodetector encapsulation packages, it is preferably used in ultraviolet light sensors, flame sensors, etc. On the other hand, it can also be used in packages encapsulating not only ultraviolet light but also visible light-receiving CCD sensors, CMOS sensors, infrared light-receiving LiDER (Laser Imaging Detection and Ranging) sensors, etc. As ultraviolet light-emitting lamps, it is preferably used in high-pressure ultraviolet lamps, low-pressure ultraviolet lamps, excimer lamps, etc. On the other hand, it can also be used in lamps that emit visible light or infrared light, not just ultraviolet light-emitting lamps.

[0080] The ultraviolet-transmitting glass of the present invention can be manufactured, for example, by mixing various glass raw materials to obtain a glass batch, melting this glass batch, clarifying and homogenizing the resulting molten glass, and then molding it into a predetermined shape.

[0081] It is preferable to use synthetic silica as part of the glass raw material, and in particular, it is preferable to use granular synthetic silica produced by a gas-phase reaction method or a liquid-phase reaction method. The average particle size of the synthetic silica is preferably 100 μm or less, more preferably 5 to 90 μm. The synthetic silica is, for example, amorphous silica, spherical silica, or a mixture thereof. Furthermore, it is preferable that the proportion of the above synthetic silica in the total silica source of the glass raw material be 90 to 100% by mass. Using such raw materials can increase the transmittance in the deep ultraviolet region.

[0082] It is preferable to use a reducing agent as part of the glass raw material. In this way, the Fe contained in the glass is reduced. 3+ The material is reduced, improving transmittance in deep ultraviolet light. Materials such as wood powder, carbon powder, metallic aluminum, metallic silicon, and aluminum fluoride can be used as reducing agents, but metallic silicon and aluminum fluoride are preferred among them.

[0083] The amount of metallic silicon added is preferably 0.001 to 3% by mass, 0.005 to 2% by mass, 0.01 to 1% by mass, 0.1 to 0.8% by mass, 0.15 to 0.5% by mass, and especially preferably 0.2 to 0.3% by mass, relative to the total mass of the glass batch. If the amount of metallic silicon added is too small, the Fe contained in the glass will be affected. 3+ If the silicon is not reduced, the transmittance under deep ultraviolet light tends to decrease. On the other hand, if too much metallic silicon is added, the glass tends to turn brown.

[0084] The amount of aluminum fluoride (AlF3) added is preferably 0.01 to 2% by mass, 0.05 to 1.5% by mass, or 0.3 to 1.5% by mass in terms of F, relative to the total mass of the glass batch. On the other hand, if too much aluminum fluoride is added, there is a risk that F gas will remain in the glass as bubbles. [Examples]

[0085] The present invention will be described below based on examples. Note that the following examples are merely illustrative. The present invention is not limited in any way to the following examples.

[0086] Tables 1-6 show examples of the present invention (samples No. 1-48) and comparative examples (samples No. 49-52).

[0087] [Table 1]

[0088] [Table 2]

[0089] [Table 3]

[0090] [Table 4]

[0091] [Table 5]

[0092] [Table 6]

[0093] First, glass batches prepared using the glass raw materials shown in the table were placed in a platinum crucible and melted at 1650°C for 4 hours to achieve the glass composition shown in the table. Aluminum fluoride was used as the raw material for introducing F.

[0094] The obtained molten glass was stirred using a platinum stirrer to homogenize it. Next, the molten glass was poured onto a carbon plate and formed into a flat plate shape, and then slowly cooled from a temperature approximately 20°C above the annealing point to room temperature at a rate of 3°C / min.

[0095] The density ρ was measured using the well-known Archimedes method. The average thermal expansion coefficient α at 30–380°C was measured using a dilatometer.

[0096] The temperature corresponding to the strain point Ps, annealing point Ta, softening point Ts, and glass viscosity Logρ = 4.0 dPa·s (10 4.0 dPa·s), glass viscosity Logρ = 3.0 dPa·s, corresponding temperature (10 3.0 dPa·s), glass viscosity Logρ = 2.5 dPa·s, corresponding temperature (10 3.0 The value of dPa·s is measured using well-known methods such as the platinum ball pulling method. The temperature corresponding to the glass viscosity Logρ = 6.0 dPa·s is (10 6.0 The dPa·s value was calculated by applying the above glass viscosity to Fulcher's formula.

[0097] The liquidus temperature TL is the temperature at which crystals precipitate after glass powder that has passed through a standard 30-mesh (500 μm) sieve and remained in a 50-mesh (300 μm) sieve is placed in a platinum boat and held in a temperature gradient furnace for 24 hours. The glass viscosity at liquidus temperature logηTL is the value obtained by measuring the viscosity of the glass at liquidus temperature TL using the platinum ball pulling method.

[0098] External transmittance was measured using a double-beam spectrophotometer, determining the spectral transmittance in the thickness direction. The sample thickness was 0.5 mm, and both sides were polished to an optically polished (mirror) finish. The surface roughness Ra of the glass surface of these samples was measured by AFM and was found to be 0.5 to 1.0 nm in a measurement area of ​​5 μm × 5 μm.

[0099] Figure 1 shows the transmittance curve of sample No. 13, which has a thickness of 0.5 mm, at wavelengths of 200 to 400 nm.

[0100] The weather resistance of each obtained sample was evaluated. First, each glass was lapped to dimensions of 20 × 35 × 2.03 mm, then polished to dimensions of 20 × 35 × 2.00 mm, and the glass surface was mirror-finished. To confirm weather resistance, a fast-accelerated life test (HAST) was performed at a temperature of 121°C, relative humidity of 85%, and for a test period of 24 hours. The fast-accelerated life test was performed using a test apparatus manufactured by Hirayama Seisakusho Co., Ltd. After the test, foreign matter on the glass surface was observed using a digital microscope manufactured by Keyence Corporation. As a result, no foreign matter was found on the glass surface of samples No. 1 to 19 and 41.

[0101] On the other hand, in samples No. 49 to 52, the glass underwent phase separation during melting or molding, resulting in opacity. Consequently, the presence of foreign matter with a maximum long side exceeding 100 μm was observed on the glass surface of samples No. 49 to 52.

[0102] In the above embodiment, molten glass was poured out to form a flat plate shape. However, for industrial-scale production, it is preferable to form the flat plate shape using an overflow down-draw method or the like, and to use it with both surfaces unpolished. Furthermore, when forming a tubular shape, it is preferable to form it using a down-draw method or the Danner method. [Industrial applicability]

[0103] The ultraviolet-transmitting glass of the present invention is suitable for use in, for example, ultraviolet light-emitting diodes (LEDs), semiconductor packages, photodetector encapsulation packages, ultraviolet light-emitting lamps, photomultiplier tubes, magnetic recording medium reading / writing devices, and other electronic devices that use ultraviolet light. Furthermore, the ultraviolet-transmitting glass of the present invention can also be applied to electronic devices that use visible light or infrared light.

Claims

1. As a glass composition, in mass %, SiO ２ 55 to 80%, Al ２ O ３ 1 to 25%, B ２ O ３ 10.8 to 30%, Li ２ O 0.6 to 5%, Na ２ O 0 to 10%, K ２ O less than 0 to 1.6%, Li ２ O + Na ２ O + K ２ O 0.8 to 10%, BaO 0 to 5%, Cl 0 to 1%, and the mass ratio Na ２ O / (Li ２ O + Na ２ O + K ２ O) is 0.10 to 0.761, the external transmittance at a thickness of 0.5 mm and a wavelength of 200 nm is 38% or more, and when a high-speed accelerated life test (HALT) is performed at a temperature of 121 °C, a relative humidity of 85%, and a test time of 24 hours, the maximum long side of the foreign matter generated on the glass surface is 100 μm or less, an ultraviolet transmitting glass.

2. The glass composition is SiO2 by mass%. ２ 65-74%, Al ２ O ３ 3.5-20%, B ２ O ３ 11.5-25%, Na ２ O 0.1-8%, K ２ O 0-1%, Li ２ O + Na ２ O+K ２ O 1-10%, BaO 0-1.9%, Cl 0.01-0.5%, Fe ２ O ３ +TiO ２ The ultraviolet-transmitting glass according to claim 1, containing 0.00001 to 0.00200%.

3. The ultraviolet-transmitting glass according to claim 1 or 2, wherein the temperature corresponding to the glass viscosity Logρ = 6.0 dPa·s is 870°C or lower.

4. An ultraviolet-transmitting glass according to any one of claims 1 to 3, wherein the temperature corresponding to the glass viscosity Logρ = 4.0 dPa·s is 1200°C or less.

5. The average coefficient of thermal expansion between 30 and 380°C is 40 × 10⁻⁶. －７ ~65 x 10 －７ An ultraviolet-transmitting glass according to any one of claims 1 to 4, wherein the temperature is / °C.

6. An ultraviolet-transmitting glass according to any one of claims 1 to 5, having a thickness of 0.5 mm and an external transmittance of 70% or more at a wavelength of 230 nm.

7. The external transmittance (%) at a thickness of 0.5 mm and a wavelength of 200 nm is T ２００ The external transmittance (%) at a thickness of 0.5 mm and a wavelength of 260 nm is T ２６０ In that case, T ２００ / T ２６０ An ultraviolet-transmitting glass according to any one of claims 1 to 6, satisfying the relationship ≥ 0.

45.

8. An ultraviolet-transmitting glass according to any one of claims 1 to 7, wherein a functional film is formed on the glass surface.

9. An ultraviolet-transmitting glass according to any one of claims 1 to 7, wherein a lens structure is formed on the glass surface.

10. An ultraviolet-transmitting glass according to any one of claims 1 to 7, wherein a prism structure is formed on the glass surface.

11. An ultraviolet-transmitting glass according to any one of claims 1 to 7, wherein an adhesive layer is formed on the glass surface.

12. An ultraviolet-transmitting glass according to any one of claims 1 to 11, wherein the shape is plate-like or tubular and the thickness is 0.1 to 3.0 mm.

13. An ultraviolet-transmitting glass according to any one of claims 1 to 12, wherein the shape is tubular and the inner diameter thereof is 1 mm or more.

14. An ultraviolet-transmitting glass according to any one of claims 1 to 13, for use in any of ultraviolet light-emitting diodes (LEDs), semiconductor packages, photodetector encapsulation packages, ultraviolet light-emitting lamps, and photomultiplier tubes.

Images