Quartz glass

Abstract

The object of the present invention is to provide at least one of a quartz glass that can transmit 222 nm light while suppressing the transmission of 252 nm light, and a method for producing the same. Quartz glass having a tin content of 5 ppm or more and 150 ppm or less, and a ratio of the absorption coefficient at a wavelength of 252 nm to the absorption coefficient at a wavelength of 222 nm of 2.5 or more.

Description

[Technical field]

[0001] The present disclosure relates to fused silica. [Background technology]

[0002] Ultraviolet light with a wavelength of around 222 nm (hereinafter referred to as "222 nm UV light") has an extremely small effect on living organisms, and sterilization and virus inactivation technologies using this light are attracting attention. KrCl excimer lamps, which are widely used as a source of 222 nm UV light, emit not only 222 nm UV light, but also ultraviolet light with a wavelength of around 252 nm (hereinafter referred to as "252 nm UV light"). Since there are concerns about the effect of 252 nm UV light on living organisms, it is necessary to block this light in order to sterilize or inactivate viruses using KrCl excimer lamps intended for living organisms.

[0003] For example, Patent Documents 1 and 2 propose a sterilization device equipped with an optical filter that blocks 252 nm UV light. Non-Patent Document 1 discloses that tin-containing quartz glass manufactured by the CVD method or the gas flame method blocks 252 nm UV light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6025756 [Patent Document 2] Patent No. 6973603 [Non-patent literature]

[0005] [Non-Patent Document 1] Glass Physics and Chemistry, Vol. 28, No. 6, 2002, pp. 379-388. Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Documents 1 and 2 disclose optical filters made of a dielectric multilayer film formed by alternately stacking 33 layers of HfO2 and SiO2 on a glass plate. However, such optical filters require complicated processes for manufacturing. Furthermore, it is difficult to form a dielectric multilayer film on a curved surface, and the wavelength range that is blocked varies depending on the irradiation angle of the light from a KrCl excimer lamp (hereinafter also referred to as "excimer light"). Therefore, the excimer light equipped with an optical filter as disclosed in Patent Documents 1 and 2 has a limited irradiation area that is effective for sterilization and virus inactivation. In addition, as is clear from FIG. 1 showing the absorption spectrum, the quartz glass disclosed in Non-Patent Document 1 blocks not only 252 nm UV light but also 222 nm UV light.

[0007] An object of the present disclosure is to provide at least one of a quartz glass that is capable of transmitting 222 nm light while suppressing the transmission of 252 nm light, and a method for producing the same. [Means for solving the problem]

[0008] The present invention is as described in the claims, and the gist of the present disclosure is as follows. [1] Quartz glass having a tin content of 5 ppm or more and 150 ppm or less, and a ratio of the absorption coefficient at a wavelength of 252 nm to the absorption coefficient at a wavelength of 222 nm of 2.5 or more. [2] The quartz glass according to [1], which has an internal linear transmittance of 70% or less for light having a wavelength of 252 nm when the thickness is 1 mm. [3] The quartz glass according to [1] or [2], which has an internal linear transmittance of 30% or more for light having a wavelength of 222 nm when the thickness is 1 mm. [4] The quartz glass according to any one of [1] to [3], wherein the internal linear transmittance of light having a wavelength of 222 nm when the thickness is 1 mm is higher than the internal linear transmittance of light having a wavelength of 252 nm when the thickness is 1 mm. [5] The absorption coefficient at a wavelength of 252 nm is 30,000 cm -1The quartz glass according to any one of [1] to [4] above. [6] The absorption coefficient at a wavelength of 222 nm is 200,000 cm -1 The quartz glass according to any one of [1] to [5] below. [7] A method for producing quartz glass according to any one of [1] to [6], comprising: a first heat treatment step of heat treating a raw material composition containing a silica source and a tin source at 20°C or higher and 1900°C or lower under a vacuum of 10 Pa or lower; and a second heat treatment step of heat treating the raw material composition heat-treated in the first heat treatment step at 1400°C or higher and 1900°C or lower under a nitrogen atmosphere. [8] The method for producing silica glass according to [7], wherein the silica source is silica powder. [9] The method for producing silica glass according to [7], wherein the silica source is a silica powder obtained by hydrolysis of silicon alkoxide. Effect of the Invention

[0009] The present disclosure makes it possible to provide at least one of quartz glass and a manufacturing method thereof that does not require an optical filter as shown in Patent Documents 1 and 2, and that, compared to conventional tin-containing quartz glass, can transmit 222 nm light while suppressing the transmission of 252 nm light. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The quartz glass according to the present disclosure will be described below with reference to an example of an embodiment. The configurations and parameters disclosed herein may be combined in any combination, and the upper and lower limits of the values ​​disclosed herein may be combined in any combination.

[0011] The silica glass of this embodiment is silica glass having a tin content of 5 ppm or more and 150 ppm or less, and a ratio of the absorption coefficient at a wavelength of 252 nm to the absorption coefficient at a wavelength of 222 nm of 2.5 or more.

[0012] The quartz glass of this embodiment has a tin content of 5 ppm to 150 ppm, so that it can transmit 222 nm light while suppressing the transmission of 252 nm light. If the tin content is less than 5 ppm, it is not possible to suppress the transmission of 252 nm light. If the tin content is more than 150 ppm, the transmission of not only 252 nm light but also 222 nm light is suppressed.

[0013] In the quartz glass of this embodiment, the content of tin is only required to be 5 ppm or more and 150 ppm or less, but from the viewpoint of further improving the balance between the suppression of the transmission of light having a wavelength of 252 nm and the transmission of light having a wavelength of 222 nm, it is preferably 10 ppm or more and 120 ppm or less, more preferably 15 ppm or more and 80 ppm or less, even more preferably 15 ppm or more and 50 ppm or less, and even more preferably 15 ppm or more and 30 ppm or less. Note that ppm in this specification means ppm by mass.

[0014] In the quartz glass of this embodiment, the tin content can be measured by the following method using ICP atomic emission spectrometry. Quartz glass is crushed and dissolved in hydrofluoric acid, and then sulfuric acid is added and heated to volatilize the hydrofluoric acid, thereby obtaining a residue for measurement. The residue for measurement is dissolved in nitric acid to obtain a sample solution. Using a general ICP atomic emission spectrometry analyzer (for example, product name: 5800 ICP-OES, manufactured by Agilent Technologies), the sample solution may be measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) under the following conditions. Frequency: 27MHz Power output: 1.2kW Observation mode: Axial Detector: CCD detector Scanning Mode: Continuous Sample introduction: Cyclone nebulizer From the obtained measured values ​​of tin and foreign metal elements, the tin content and foreign metal element content of the quartz glass can be determined.

[0015] In the quartz glass of this embodiment, tin may be contained in any form, such as ions, metal, or compounds (e.g., oxides), but is preferably contained in the form of an oxide (e.g., SnO2).

[0016] The quartz glass of this embodiment has a ratio of the absorption coefficient of 252 nm to the absorption coefficient of 222 nm of 2.5 or more. From the viewpoint of further improving the balance between the suppression of transmission of light of 252 nm and the transmission of light of 222 nm, the quartz glass of this embodiment has a ratio of the absorption coefficient of 252 nm to the absorption coefficient of 222 nm of 3.0 or more, and more preferably 4.0 or more. In the quartz glass of this embodiment, the upper limit of the ratio of the absorption coefficient of 252 nm to the absorption coefficient of 222 nm is not particularly limited, but can be, for example, 20 or less, 10 or less, or 7.0 or less. The ratio of the absorption coefficient at a wavelength of 252 nm to the absorption coefficient at a wavelength of 222 nm may be any combination of the upper and lower limits described above. From the viewpoint of further improving the balance between the suppression of transmission of light at a wavelength of 252 nm and the transmission of light at a wavelength of 222 nm, the ratio is preferably 2.5 or more and 20 or less, more preferably 3.0 or more and 10 or less, and even more preferably 4.0 or more and 7.0 or less.

[0017] The absorption coefficient of the silica glass of this embodiment is an absorption coefficient obtained by correcting and removing the effects of light scattered by bubbles in the silica glass and light reflected at the surface (interface) of the silica glass, and can be calculated from the following formula (1). The absorption coefficient at a wavelength of 252 nm (hereinafter referred to as "α 252nm ") is calculated by dividing the absorption coefficient at a wavelength of 222 nm (hereinafter referred to as "α 222nm ") to obtain α 222nm α for 252nm The ratio of (hereinafter, "α 252nm / α 222nm The absorption coefficient is a parameter that indicates how much light a medium absorbs when light enters it, and a higher absorption coefficient means that a smaller amount of light passes through the silica glass.

[0018] -LOG(T i ) = α × d × c (1) In the above formula (1), T i represents the internal linear transmittance [%] of the quartz glass for light of wavelength W (nm), and α represents the absorption coefficient [cm -1 ], d represents the thickness of the measurement sample [cm], and c represents the tin content in the quartz glass [g / g].

[0019] Ti in the above formula (1) can be calculated from the following formula (2). T i =100×T c / T M (2) In the above formula (2), T i represents the internal linear transmittance [%] of the quartz glass for light of wavelength W (nm), and T c represents the linear transmittance [%] of the measured sample for light of wavelength W (nm) corrected for the effect of light scattering by air bubbles, and T M represents the theoretical linear transmittance [%] of silica glass for light of wavelength W (nm), calculated from the following formula (7).

[0020] T in the above formula (2) c can be calculated from the following formula (3). T c =T×T M(790-800nm) / T (790-800nm) (3) In the above formula (3), T c represents the linear transmittance [%] of the measured sample for light of wavelength W (nm) corrected for the effect of light scattering by air bubbles, T represents the actual linear transmittance [%] of the measured sample for light of wavelength W (nm), and T M(790-800nm) represents the average theoretical linear transmittance [%] of quartz glass for light with wavelengths between 790 nm and 800 nm, calculated from the following formula (4), and T (790-800nm) represents the average value [%] of the actual in-line transmittance of the measured sample for light with wavelengths from 790 nm to 800 nm.

[0021] T in the above formula (3) can be obtained by measuring the actual linear transmittance [%] of a measurement sample for light of wavelength W (nm) using an ultraviolet-visible spectrophotometer under the conditions described below.

[0022] T in the above formula (3) M(790-800nm) can be calculated from the following formula (4). TIFF0007593536000001.tif12156In the above formula (4), T M(790-800nm) represents the average theoretical linear transmittance [%] of the quartz glass for light with wavelengths from 790 nm to 800 nm, and R represents the surface reflectance [-] of the quartz glass for light with wavelength i (nm) calculated from the following formula (5). Note that, as can be understood from the above formula (4), wavelength i (nm) represents each wavelength in 1 (nm) increments within the range of 790 (nm) to 800 (nm).

[0023] R in the above formula (4) can be calculated from the following formula (5). R = (1-N) 2 / (1+N) 2 (5) In the above formula (5), R represents the surface reflectance [-] of the quartz glass for light of wavelength i (nm), and N represents the refractive index [-] of the quartz glass for light of wavelength i (nm) calculated from the following formula (6) (Malitson's formula).

[0024] N in the above formula (5) can be calculated from the following formula (6). N 2 =1+a1×λ 2 / (λ 2 -b1)+a2×λ 2 / (λ 2 -b2) +a3×λ 2 / (λ 2 -b3) (6) In the above formula (6), N represents the refractive index [-] of the silica glass for light of wavelength i (nm), λ represents the wavelength i [nm], and a1 to a3 and b1 to b3 represent a1 = 0.6961663, a2 = 0.4079426, a3 = 0.8974794, b1 = 0.0684043, b2 = 0.1162414, and b3 = 9.896161, respectively.

[0025] T in the above formula (3) (790-800nm) The transmittance can be determined by measuring a sample using an ultraviolet-visible spectrophotometer under the conditions described below, and averaging the measured linear transmittance at each wavelength in 1 nm increments within the wavelength range of 790 nm or more and 800 nm or less.

[0026] T in the above formula (2) M can be calculated from the following equation (7). T M =100×(1-R) 2 (7) In the above formula (7), T M represents the theoretical linear transmittance [%] of the quartz glass for light of wavelength W (nm), and R represents the surface reflectance [-] of the quartz glass for light of wavelength W (nm) calculated by the following formula (8).

[0027] R in the above formula (7) can be calculated from the following formula (8). R = (1-N) 2 / (1+N) 2 (8) In the above formula (8), R represents the surface reflectance [-] of the quartz glass for light of wavelength W (nm), and N represents the refractive index [-] of the quartz glass for light of wavelength W (nm) calculated from the following formula (9).

[0028] N in the above formula (8) can be calculated from the following formula (9). N 2 =1+a1×λ 2 / (λ 2 -b1)+a2×λ 2 / (λ 2 -b2) +a3×λ2 / (λ 2 -b3) ···(9) In the above formula (9), N represents the refractive index [-] of the silica glass for light of wavelength W (nm), λ represents the wavelength W [nm], and a1 to a3 and b1 to b3 represent a1 = 0.6961663, a2 = 0.4079426, a3 = 0.8974794, b1 = 0.0684043, b2 = 0.1162414, and b3 = 9.896161, respectively.

[0029] T and T in the above formula (3) (790-800nm) The following measurement conditions can be used for the measurement of the measurement sample by the UV-Vis spectrophotometer used for the calculation of . In the measurement by the UV-Vis spectrophotometer, the light transmission direction is the thickness direction of the measurement sample. In addition, the UV-Vis spectrophotometer used for the measurement can be a UV-Vis spectrophotometer commonly used in the technical field, for example, V-770 manufactured by JASCO Corporation. Data capture interval: 1 nm Bandwidth: 5.0nm Response time: 0.06 seconds Light source: Deuterium lamp, halogen lamp Scanning Mode: Continuous Scanning speed: 400nm / min Measurement range: 200nm to 900nm

[0030] For the measurement sample to be measured by the UV-Vis spectrophotometer, surface-polished quartz glass (quartz glass of the present embodiment) having a thickness of 0.1 mm to 5.0 mm can be used. The quartz glass to be used as the measurement sample may be cut to a predetermined thickness or less, and then the surface may be polished to a thickness of 0.1 mm to 5.0 mm. For surface polishing of the quartz glass, a polishing machine generally used in the technical field, such as LaboPol 30 manufactured by Struers, may be used, and it is preferable to polish the quartz glass surface to a smooth surface until the arithmetic mean roughness Ra of the quartz glass surface is 3 nm or less. Surface polishing of the quartz glass may be performed on at least two surfaces, the surface where the light to be transmitted through the quartz glass enters (hereinafter also referred to as the "incident surface") in the measurement by the UV-Vis spectrophotometer, and the surface where the light to be transmitted through the quartz glass exits (hereinafter referred to as the "exit surface"). For cutting the quartz glass, a general surface grinder (for example, product name: PSG-52SA1, manufactured by Okamoto Machine Tool Works, Ltd.) may be used. The arithmetic mean roughness Ra of the quartz glass surface (i.e., the surface of the measurement sample) may be measured using a general surface roughness measuring device (for example, product name: optical surface texture measuring device ZYGO New View 7100, manufactured by ZYGO Corporation) in accordance with JIS B 0601-2001 under the following conditions. Measurement magnification: Objective lens x 50x, zoom x 1x Measurement range: 172μm×141μm

[0031] The silica glass of the present embodiment has a tin content of 5 ppm or more and 150 ppm or less, and α 252nm / α 222nm If is 2.5 or more, α 252nm Or alpha 222nm Other configurations such as those mentioned above are not particularly limited.

[0032] From the viewpoint of making the transmitted light more suitable for irradiation of a living body, the α 252nm is 30000cm -1 It is preferable that the viscosity is 40,000 cm or more. -1 More preferably, it is 90,000 cm or more. -1More preferably, it is 150,000 cm or more. -1 It is particularly preferable that α is equal to or larger than α. 252nm The upper limit of is not particularly limited, but is, for example, 700000 cm -1 Below, 600000cm -1 Below, 500000cm -1 or less than 400,000 cm -1 It can be expressed as follows: α 252nm may be any combination of the upper and lower limits described above, but from the viewpoint of making the transmitted light more suitable for irradiation of a living body, 30000 cm -1 More than 700000cm -1 Preferably, it is 40,000 cm or less. -1 More than 600000cm -1 More preferably, it is 90,000 cm or less. -1 More than 500000cm -1 Even more preferably, it is 150,000 cm or less. -1 More than 400000cm -1 It is particularly preferred that:

[0033] From the viewpoint of further improving the sterilization performance and virus inactivation performance by the transmitted light, the α of the quartz glass of this embodiment is 222nm is 200000cm -1 Preferably, it is 150,000 cm or less. -1 More preferably, it is 100,000 cm or less. -1 Even more preferably, it is equal to or less than 80000 cm -1 It is particularly preferable that α is equal to or less than 1. 222nm The lower limit is not particularly limited, but may be, for example, 5000 cm -1 More than 10000cm -1 More than 15000cm -1 or more than 20,000 cm -1 It can be more than α 222nm may be any combination of the upper and lower limits described above, but from the viewpoint of further improving the sterilization performance and virus inactivation performance by the transmitted light, it is preferable to use a value of 5000 cm -1More than 200000cm -1 Preferably, it is 10,000 cm or less. -1 More than 150000cm -1 More preferably, it is 15,000 cm or less. -1 More than 100000cm -1 Even more preferably, it is equal to or less than 20,000 cm -1 More than 80000cm -1 It is particularly preferred that:

[0034] The silica glass of the present embodiment has a tin content of 5 ppm or more and 150 ppm or less, and α 252nm / α 222nm As long as the ratio is 2.5 or more, the composition is not particularly limited. For example, the quartz glass of the present embodiment may be composed of only tin and silica (SiO2), or may contain one or more other components in addition to tin and silica (SiO2). From the viewpoint of further improving the transmission of 222 nm light, it is preferable that the quartz glass of the present embodiment is composed of only tin and silica (SiO2). In particular, from the viewpoint of further improving the transmission of 222 nm light, it is preferable that the quartz glass of the present embodiment does not contain alkali metals, alkaline earth metals, and transition metals (hereinafter, these are also collectively referred to as "foreign metal elements"). Not containing foreign metal elements means that the content of foreign metal elements in the quartz glass of the present embodiment is equal to or less than the detection limit, and although it depends on the detection ability of the measuring device, it can be, for example, 0 ppm or more and 3 ppm or less. The content of foreign metal elements in the quartz glass of the present embodiment is more preferably more than 0 ppm and 3 ppm or less, and particularly preferably more than 0 ppm and 2 ppm or less. Moreover, the content of foreign metal elements being 0 ppm means that no foreign metal elements are contained.

[0035] The silica glass of the present embodiment has a tin content of 5 ppm or more and 150 ppm or less, and α 252nm / α 222nmThe linear transmittance is not particularly limited as long as it is 2.5 or more. From the viewpoint of making the transmitted light more suitable for irradiation of a living body, the quartz glass of this embodiment preferably has an internal linear transmittance of light with a wavelength of 252 nm when the thickness is 1 mm (hereinafter also referred to as "internal linear transmittance 252 nm") of 70% or less, more preferably 50% or less, and particularly preferably 40% or less. In addition, from the viewpoint of further improving the sterilization performance and virus inactivation performance of the transmitted light, the quartz glass of this embodiment preferably has an internal linear transmittance of light with a wavelength of 222 nm when the thickness is 1 mm (hereinafter also referred to as "internal linear transmittance 222 nm") of 30% or more, more preferably 50% or more, and particularly preferably 70% or more.

[0036] In the quartz glass of this embodiment, the lower limit of the internal linear transmittance 252 nm when the thickness is 1 mm is not particularly limited, and can be, for example, 0% or more. In the quartz glass of this embodiment, the upper limit of the internal linear transmittance 222 nm when the thickness is 1 mm is not particularly limited, and can be, for example, 100% or less.

[0037] The internal linear transmittance of the quartz glass of this embodiment is a linear transmittance corrected and removed for the effects of light scattered by bubbles in the quartz glass and light reflected at the surface (interface) of the quartz glass. In the quartz glass of this embodiment, the internal linear transmittance at a thickness of 1 mm is calculated by multiplying the thickness d of the measurement sample (the thickness of the measurement sample measured by an ultraviolet-visible spectrophotometer) by the T calculated by the above formula (2). i It can be calculated from the following formula (10). T 1mm =(T i / 100) 0.1 / d ×100 ···(10) In the above formula (10), T 1mm represents the internal linear transmittance [%] of light with wavelength W (nm) through quartz glass with a thickness of 1 mm, and T i represents the internal linear transmittance [%] of the quartz glass for light of wavelength W (nm), and d represents the thickness [cm] of the measurement sample.

[0038] In the quartz glass of this embodiment, the light with a wavelength of 222 nm is more easily transmitted, and the more the transmission of the light with a wavelength of 252 nm is suppressed, the better the balance between the suppression of the transmission of the light with a wavelength of 252 nm and the transmission of the light with a wavelength of 222 nm is. Therefore, in the quartz glass of this embodiment, the internal linear transmittance 222 nm at a thickness of 1 mm is preferably higher than the internal linear transmittance 252 nm at a thickness of 1 mm, more preferably 20% or more higher than the internal linear transmittance 252 nm at a thickness of 1 mm, even more preferably 30% or more higher than the internal linear transmittance 252 nm at a thickness of 1 mm, and particularly preferably 40% or more higher than the internal linear transmittance 252 nm at a thickness of 1 mm. In addition, the upper limit of the difference (internal linear transmittance 222 nm - internal linear transmittance 252 nm) obtained by subtracting the internal linear transmittance 252 nm at a thickness of 1 mm from the internal linear transmittance 222 nm at a thickness of 1 mm is not particularly limited, but can be, for example, 80% or less, 70% or less, 60% or less, or 50% or less.

[0039] The form of the quartz glass of this embodiment is not particularly limited, but it is preferably a single layer of quartz glass since it does not require a complicated manufacturing process.

[0040] Here, the α of quartz glass 252nm / α 222nm does not change depending only on the content of components (such as tin) contained in the quartz glass, but also on other factors, such as the manufacturing method. Therefore, even if the tin content of the quartz glass is 5 ppm or more and 150 ppm or less, the α of the quartz glass 252nm / α 222nm Therefore, the quartz glass of the present embodiment has a tin content of 5 ppm or more and 150 ppm or less, and α 252nm / α 222nm The manufacturing method is such that the tin content is 5 ppm or more and 150 ppm or less, and α is 2.5 or more. 252nm / α 222nmAn example of a method for producing quartz glass having a refractive index of 2.5 or more (that is, the quartz glass of this embodiment) will be described.

[0041] The quartz glass of this embodiment can be produced by a production method including a first heat treatment step of heat-treating a raw material composition containing a silica source and a tin source at a temperature of 20°C or higher and 1900°C or lower under a vacuum of 10 Pa or lower, and a second heat treatment step of heat-treating the raw material composition heat-treated in the first heat treatment step at a temperature of 1400°C or higher and 1900°C or lower under a nitrogen atmosphere.

[0042] The silica source contained in the raw material composition can be exemplified by silica powder. The silica powder as the silica source can be one or more selected from the group consisting of commercially available silica powder, silica powder obtained by hydrolysis of silicon alkoxide, and silica powder obtained by hydrolysis of silicon tetrachloride with an oxyhydrogen flame or the like.

[0043] The tin source contained in the raw material composition can be exemplified by a tin compound. Specific examples of the tin compound include one or more selected from the group consisting of tin oxide (SnO2), tin chloride (IV), tin hydroxide (IV) and tin sulfate (II), and tin oxide is preferred. The tin compound is preferably in the form of a powder in order to mix more uniformly with the silica source. The content of the tin source in the raw material composition may be an amount that allows the tin content in the produced quartz glass to be 5 ppm or more and 150 ppm or less, and can be appropriately adjusted.

[0044] The raw material composition may be a simple mixture of each raw material (silica source and tin source), or may be a tin compound-containing silica powder obtained by a sol-gel method. The method for producing the tin compound-containing silica powder is not particularly limited, and may be a method for producing silica powder by a conventionally known sol-gel method, in which a tin compound is added to a reaction solution in which a sol-gel reaction is carried out.

[0045] An example of a specific method for producing a tin-containing silica powder is a method in which a sol-gel reaction is carried out in a reaction solution obtained by mixing at least a tin compound, a silicon alkoxide, and water to obtain a tin compound-containing silica gel, the obtained tin compound-containing silica gel is dried to obtain a tin compound-containing dry silica gel, and the obtained tin compound-containing dry silica gel is calcined to produce a tin compound-containing silica powder.

[0046] In the above-mentioned method for producing a tin compound-containing silica powder, the content ratio of silicon alkoxide and water (silicon alkoxide:water) in the reaction solution can be a conventionally known content ratio, for example, it can be 10:1 to 1:1 by mass ratio. The content of the tin compound in the reaction solution can be appropriately set as long as the tin content in the produced quartz glass is 5 ppm or more and 150 ppm or less.

[0047] In the above-mentioned method for producing a tin compound-containing silica powder, the tin compound-containing silica gel can be dried under conventionally known drying conditions, for example, drying in air at 40°C to 150°C for 1 hour to 10 hours. In addition, in the above-mentioned method for producing a tin compound-containing silica powder, the tin compound-containing dried silica gel can be calcined under conventionally known calcination conditions, for example, calcination in air at 600°C to 1300°C for 1 hour to 10 hours.

[0048] In the above-mentioned method for producing a tin compound-containing silica powder, the reaction solution in which the sol-gel reaction is carried out needs only to contain at least a tin compound, a silicon alkoxide, and water. From the viewpoint of promoting the sol-gel reaction, however, it is preferable that the reaction solution further contains, in addition to these, one or more components selected from the group consisting of an acid, an alkali, and a solvent.

[0049] Examples of the acid that can be contained in the reaction solution include one or more selected from the group consisting of hydrochloric acid, nitric acid, and sulfuric acid, and at least one of hydrochloric acid and sulfuric acid is preferred, and hydrochloric acid is more preferred. Examples of the alkali that can be contained in the reaction solution include one or more selected from the group consisting of ammonia, methylamine, and dimethylamine, and ammonia is preferred. Examples of the solvent that can be contained in the reaction solution include one or more selected from the group consisting of ethanol, methanol, and propanol. The content of the acid in the reaction solution can be a content that is conventionally known, and can be, for example, 0.001 mol / L or more and 1 mol / L or less, and preferably 0.001 mol / L or more and 0.1 mol / L or less. The content of the alkali in the reaction solution can be a content that is conventionally known, and can be, for example, 0.001 mol / L or more and 1 mol / L or less, and preferably 0.1 mol / L or more and 1 mol / L or less. The content of the solvent in the reaction solution can be, for example, 30 vol. % or more and 80 vol. % or less, and preferably 40 vol. % or more and 60 vol. % or less, relative to 100 vol. % of the reaction solution.

[0050] The raw material composition may be composed only of the above-mentioned silica source and tin source, but in addition to these, it may also contain one or more other components other than the silica source and the tin source.

[0051] For the raw material composition, a mixture of the raw materials (the silica source, the tin source, and other components contained as necessary) may be used as is, or a molded body obtained by molding the mixture of the raw materials into a predetermined shape by a method such as compression may be used.

[0052] In the first heat treatment step, the heat treatment of the raw material composition is carried out at 20° C. or higher and 1900° C. or lower. The heat treatment temperature of the raw material composition in the first heat treatment step may be 20° C. or higher and 1900° C. or lower, but is preferably 20° C. or higher and 1700° C. or lower, more preferably 20° C. or higher and 1600° C. or lower, even more preferably 1000° C. or higher and 1600° C. or lower, and particularly preferably 1400° C. or higher and 1600° C. or lower.

[0053] In the first heat treatment step, the raw material composition is heat-treated under a vacuum of 10 Pa or less. The pressure during the heat treatment of the raw material composition in the first heat treatment step may be 10 Pa or less, but is preferably 0.1 Pa or more and 10 Pa or less. The pressure during the heat treatment can be adjusted, for example, by degassing the air from a heat treatment container containing the raw material composition.

[0054] The heat treatment time of the raw material composition in the first heat treatment step can be, for example, from 10 minutes to 300 minutes, and is preferably from 30 minutes to 90 minutes.

[0055] In the second heat treatment step, the raw material composition heat-treated in the first heat treatment step is heat-treated in a nitrogen atmosphere at 1400°C or higher and 1900°C or lower. The second heat treatment step is only required to heat-treat the raw material composition heat-treated in the first heat treatment step under the above-mentioned conditions, and the timing of carrying out the second heat treatment step is not particularly limited, but it is preferable to carry out the second heat treatment step subsequent to the first heat treatment step. In other words, the heat treatment in the second heat treatment step is preferably carried out immediately after the heat treatment in the first heat treatment step is completed (before the raw material composition heat-treated in the first heat treatment step is cooled).

[0056] In the second heat treatment step, the heat treatment of the raw material composition is carried out at 1400° C. or higher and 1900° C. or lower. The heat treatment temperature of the raw material composition in the second heat treatment step may be 1400° C. or higher and 1900° C. or lower, but is preferably 1500° C. or higher and 1800° C. or lower, and more preferably 1700° C. or higher and 1800° C. or lower.

[0057] In the second heat treatment step, the heat treatment of the raw material composition is performed in a nitrogen atmosphere. The nitrogen atmosphere is an atmosphere in which the excess space (space excluding the raw material composition) of the container in which the raw material composition is stored is replaced with nitrogen gas, and does not exclude gases other than nitrogen that are unintentionally mixed in. For example, the nitrogen atmosphere may be created by introducing nitrogen gas into a heat treatment container in which the internal pressure is set to 10 Pa or less in the first heat treatment step.

[0058] The pressure during the heat treatment of the raw material composition in the second heat treatment step can be, for example, 100,000 Pa or more and 980,000 Pa or less, and is preferably 100,000 Pa or more and 200,000 Pa or less.

[0059] The heat treatment time of the raw material composition in the second heat treatment step can be, for example, from 10 minutes to 120 minutes, and is preferably from 10 minutes to 90 minutes.

[0060] The raw material composition is heat-treated in the second heat treatment step to produce the quartz glass of this embodiment. Note that in the second heat treatment step, the quartz glass obtained by the heat treatment may be left in a nitrogen atmosphere to cool, and the quartz glass cooled in a nitrogen atmosphere may be used as the quartz glass of this embodiment.

[0061] The quartz glass of this embodiment can be manufactured by a manufacturing method including the above-mentioned first heat treatment step and second heat treatment step.

[0062] The silica glass of the present embodiment described above can transmit 222 nm light while suppressing the transmission of 252 nm light. The reason why the silica glass of the present embodiment can transmit 222 nm light while suppressing the transmission of 252 nm light is not clear, but it is believed that the tin content is 5 ppm or more and 150 ppm or less, and α 252nm / α 222nmIt is presumed that the dispersion state of tin in the quartz glass and the state of the quartz are changed to a state that not only suppresses the transmission of 252 nm UV light but also allows the transmission of 222 nm UV light when the ratio is 2.5 or more. Such a quartz glass of the present embodiment can be applied to, for example, an optical filter for excimer light. EXAMPLES

[0063] The present disclosure will be described below with reference to examples, but the present disclosure is not limited to these examples.

[0064] (tin content) Quartz glass was crushed and dissolved in hydrofluoric acid, sulfuric acid was added, and the hydrofluoric acid was evaporated by heating to obtain a residue for measurement. This residue for measurement was dissolved in nitric acid to prepare a sample solution. The sample solution was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) under the following conditions using a general ICP atomic emission spectrometer (product name: 5800 ICP-OES, manufactured by Agilent Technologies). Frequency: 27MHz Power output: 1.2kW Observation mode: Axial Detector: CCD detector Scanning Mode: Continuous Sample introduction: Cyclone nebulizer From the obtained measured values ​​of tin and foreign metal elements, the tin content and the foreign metal element content of the quartz glass were determined.

[0065] (Measurement sample) A disk-shaped quartz glass with a diameter of 24 mm and a thickness of 8 mm was prepared, and a measurement sample having a thickness that allows the linear transmittance to be measured using an ultraviolet-visible spectrophotometer (device name: V-770, manufactured by JASCO Corporation) was prepared. That is, the quartz glass was ground to a thickness of 0.5 mm to 3.5 mm while visually checking the quartz glass using a precision surface grinder (device name: PSG-52SA1, manufactured by Okamoto Machine Tool Works, Ltd.). The ground quartz glass was further polished using a polishing machine (Labopol 30, manufactured by Struers) until it was thinned to a thickness of 0.2 mm, and a measurement sample with an arithmetic average roughness Ra of 3 nm or less on the surfaces (entrance surface and exit surface) was obtained. The arithmetic mean roughness Ra of the measurement sample surface (incident surface and exit surface) was measured using a general surface roughness measuring device (product name: optical surface texture measuring device ZYGO New View 7100, manufactured by ZYGO Corporation) in accordance with JIS B 0601-2001 under the following conditions. Measurement magnification: Objective lens x 50x, zoom x 1x Measurement range: 172μm×141μm

[0066] (Extinction coefficient) Using an ultraviolet-visible spectrophotometer (instrument name: V-770, manufactured by JASCO Corporation), the test sample was measured under the following conditions, and the measured linear transmittance [%] of the test sample for light with a wavelength of 222 nm (T in the above formula (3)), the measured linear transmittance [%] of the test sample for light with a wavelength of 252 nm (T in the above formula (3)), and the average value [%] of the measured linear transmittance of the test sample for light with wavelengths of 790 nm to 800 nm (T in the above formula (3)) were calculated. (790-800nm) The light transmission direction was the thickness direction of the sample. Data capture interval: 1 nm Bandwidth: 5.0nm Response time: 0.06 seconds Light source: Deuterium lamp, halogen lamp Scanning Mode: Continuous Scanning speed: 400nm / min Measurement range: 200nm to 900nm

[0067] The tin content (c in the above formula (1)), the measured linear transmittance [%] of the measured sample for light with a wavelength of 222 (nm) (T in the above formula (3)), and the average value [%] of the measured linear transmittance of the measured sample for light with wavelengths of 790 nm to 800 nm (T in the above formula (3)) were determined by the above method. (790-800nm) ), and the wavelength W (nm) is set to 222 (nm) (i.e., W = 222), the absorption coefficient (α 222nm Similarly, the tin content (c in the above formula (1)), the measured linear transmittance [%] of the measured sample for light with a wavelength of 252 (nm) (T in the above formula (3)), and the average value [%] of the measured linear transmittance of the measured sample for light with wavelengths of 790 nm to 800 nm (T in the above formula (3)) were determined by the above-mentioned method. (790-800nm) ), and the wavelength W(nm) is set to 252(nm) (i.e., W=252), the absorption coefficient (α 252nm ) was obtained. In addition, the obtained α 252nm α 222nm By dividing by α, the ratio of the absorption coefficient at 252 nm to the absorption coefficient at 222 nm is obtained. 252nm / α 222nm ) was sought.

[0068] (Internal linear transmittance at a thickness of 1 mm) α 222nm Using the internal linear transmittance [%] of the quartz glass for light with a wavelength of 222 nm (Ti in the above formula (10) (the above formula (2))) and the thickness [cm] of the measurement sample (d in the above formula (10)) obtained in the process of calculating α, the internal linear transmittance [%] of the quartz glass for light with a wavelength of 222 nm at a thickness of 1 mm was calculated from the above formula (10). 252nmUsing the internal linear transmittance [%] of the quartz glass for light with a wavelength of 252 nm (Ti in the above formula (10) (the above formula (2))) obtained in the calculation process and the thickness [cm] of the measurement sample (d in the above formula (10)), the internal linear transmittance [%] of the quartz glass for light with a wavelength of 252 nm when the thickness is 1 mm was calculated from the above formula (10).

[0069] Example 1 Commercially available silica powder (product name: MKC Silica PS100, manufactured by Mitsubishi Chemical Corporation) was jet milled to obtain 100 g of silica powder with an average particle size D50 (median diameter) of 5 μm or less. Tin oxide (SnO2) powder (manufactured by SIGMA-ALDRICH Corporation) was mixed with the silica powder and tin oxide (SnO2) powder so that the Sn content was 30 ppm (0.003 mass%) to obtain a mixed powder of silica powder and tin oxide (SnO2), which was used as the raw material powder.

[0070] 8.0 g of the obtained raw material powder was filled into a die with a diameter of 30 mm, and then subjected to a pressure of 150 kgf / cm 2 A pressure of 10 ...

[0071] The quartz glass of this example had a tin content of 7.4 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 62405 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 250275 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 4.01, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 65.3%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 89.9%.

[0072] Example 2 The quartz glass of this example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 50 ppm (0.005 mass%).

[0073] The quartz glass of this example had a tin content of 8.9 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 77834 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 324405 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 4.17, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 51.4%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 85.3%.

[0074] Example 3 The quartz glass of this example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 70 ppm (0.007 mass%).

[0075] The quartz glass of this example had a tin content of 13 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 48927 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 227271 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 4.65, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 50.6%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 86.4%.

[0076] Example 4 The quartz glass of this example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 100 ppm (0.01 mass%).

[0077] The quartz glass of this example had a tin content of 18 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 50243 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 248744 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 4.95, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 35.7%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 81.2%.

[0078] Example 5 The quartz glass of this example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 200 ppm (0.02 mass%).

[0079] The quartz glass of this example had a tin content of 36 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 73574 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 200252 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 2.72, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 19.0%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 54.3%.

[0080] Example 6 The quartz glass of this example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 300 ppm (0.03 mass%).

[0081] The quartz glass of this example had a tin content of 67 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 52323 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 159016 cm -1 , the ratio of the extinction coefficients (α252nm / α 222nm ) was 3.04, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 8.6%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 44.6%.

[0082] Example 7 The quartz glass of this example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 500 ppm (0.05 mass%).

[0083] The quartz glass of this example had a tin content of 100 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 41969 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 135066 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 3.22, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 4.5%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 38.0%.

[0084] Example 8 200 mL of ethanol (special grade, Junsei Chemical Co., Ltd.) and 150 mL of tetraethoxysilane (Tokyo Chemical Industry Co., Ltd.) were mixed to obtain an ethanol solution, to which 50 mL of pure water, 1 mL of 2 mol / L hydrochloric acid (Fujifilm Wako Pure Chemical Co., Ltd.), and 0.0117 g of tin chloride pentahydrate (Fujifilm Wako Pure Chemical Co., Ltd.) were added. 5 mL of 28% aqueous ammonia solution (Fujifilm Wako Pure Chemical Co., Ltd.) was further added and mixed to obtain a mixed solution. The obtained mixed solution was dried overnight at 120°C in air, and then further calcined at 800°C in air for 1 hour to obtain a tin-containing silica powder. The obtained tin-containing silica powder had an Sn content of 100 ppm (0.01% by mass) relative to the silica powder.

[0085] The quartz glass of this example was obtained in the same manner as in Example 1, except that the obtained tin-containing silica powder was used as a raw material powder and the treatment in a nitrogen atmosphere was performed at 1800° C. for 60 minutes.

[0086] The quartz glass of this example had a tin content of 56 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this example had an absorption coefficient of 24205 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 90927 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 3.76, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 30.7%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 73.2%.

[0087] Comparative Example 1 The quartz glass of this comparative example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 10 ppm (0.001 mass%).

[0088] The quartz glass of this comparative example had a tin content of 3.4 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this comparative example had an absorption coefficient of 95318 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 149698 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 1.57, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 88.9%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 92.8%.

[0089] Comparative Example 2 The quartz glass of this comparative example was obtained in the same manner as in Example 1, except that SnO2 powder (manufactured by SIGMA-ALDRICH) was mixed in such that the Sn content of the raw material powder was 1000 ppm (0.1 mass %).

[0090] The quartz glass of this comparative example had a tin content of 160 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this comparative example had an absorption coefficient of 44609 cm at 222 nm. -1, the extinction coefficient at 252 nm is 186948 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 4.19, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 0.1%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 19.3%.

[0091] Comparative Example 3 The quartz glass of this comparative example was obtained in the same manner as in Example 1, except that no SnO2 powder was mixed.

[0092] The quartz glass of this comparative example had a tin content of 0 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). The quartz glass of this comparative example also had an internal linear transmittance of 97.3% at a wavelength of 252 nm when the thickness was 1 mm, and an internal linear transmittance of 98.6% at a wavelength of 222 nm when the thickness was 1 mm.

[0093] Comparative Example 4 Commercially available silica powder (product name: MKC Silica PS100, manufactured by Mitsubishi Chemical Corporation) was jet milled to obtain 100 g of silica powder with an average particle size D50 (median diameter) of 5 μm or less. Tin oxide (SnO2) powder (manufactured by SIGMA-ALDRICH Corporation) was mixed with the silica powder and tin oxide (SnO2) powder so that the Sn content was 200 ppm (0.02 mass%) to obtain a mixed powder of silica powder and tin oxide (SnO2), which was used as the raw material powder.

[0094] 8.0 g of the obtained raw material powder was filled into a die with a diameter of 30 mm, and then subjected to a pressure of 150 kgf / cm 2 A pressure of 10 ...

[0095] The quartz glass of this comparative example had a tin content of 39 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this comparative example had an absorption coefficient of 527569 cm at 222 nm.-1 , the extinction coefficient at 252 nm is 532745 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 1.01, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 0.8%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 0.9%.

[0096] Comparative Example 5 A tin-containing silica powder was obtained in the same manner as in Example 8. 8.0 g of the obtained raw material powder was filled into a die having a diameter of 30 mm, and then subjected to a pressure of 150 kgf / cm 2 A pressure of 100000000000 was applied for 30 seconds to form the molded body. The molded body was placed in a carbon container, nitrogen was introduced at 130 kPa, and the molded body was treated in a nitrogen atmosphere at 1575°C for 60 minutes, and then further treated in the nitrogen atmosphere at 1800°C for 20 minutes. The molded body was then left to cool naturally overnight in the nitrogen atmosphere to obtain the quartz glass of this comparative example.

[0097] The quartz glass of this comparative example had a tin content of 33 ppm and a foreign metal element content of 2 ppm or less (below the detection limit). In addition, the quartz glass of this comparative example had an absorption coefficient of 766237 cm at 222 nm. -1 , the extinction coefficient at 252 nm is 681667 cm -1 , the ratio of the extinction coefficients (α 252nm / α 222nm ) was 0.89, the internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm was 0.6%, and the internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm was 0.3%.

[0098] The evaluation results of the examples and comparative examples are shown in Table 1 below. [Table 1]

[0099] As can be seen from Table 1 above, the quartz glass of each Example had a lower internal linear transmittance at a wavelength of 252 nm when the thickness was 1 mm than Comparative Example 1, in which the tin content was 3.4 ppm. Also, the quartz glass of each Example had a higher internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm than Comparative Example 2, in which the tin content was 160 ppm. Furthermore, the quartz glass of each Example had a higher internal linear transmittance at a wavelength of 222 nm when the thickness was 1 mm than the quartz glasses of Comparative Examples 4 and 5. From this result, it was understood that the quartz glass of each Example can transmit light of 222 nm while suppressing the transmission of light of 252 nm.

[0100] (UV irradiation test with a peak wavelength of 254 nm on fibroblast cells) Normal human adult skin fibroblasts (Kuraray Industries, Inc.) were placed in a 96-well plate (transparent plate) at 3.3 × 10 3 The cells were seeded at 1000 cells / well and cultured overnight. After overnight culture, a 96-well plate was fixed onto the quartz glass (thickness 3.0 mm) of each Example and Comparative Example. An ultraviolet ray irradiation device (device name: Handy UV Lamp, manufactured by AS ONE Corporation) was positioned so that the distance from the bottom of the 96-well plate to the irradiation surface was 50 mm, and ultraviolet rays with a peak wavelength of 254 nm (ultraviolet rays containing light of 252 nm) were irradiated so that the ultraviolet rays that passed through the quartz glass were irradiated onto normal human adult skin fibroblasts. The ultraviolet ray irradiation was performed in a clean bench with the lid of the 96-well plate removed, and three conditions with different irradiation doses (10 J / cm 2 , 15J / cm 2 , or 20 mJ / cm 2 As a control, normal human adult skin fibroblasts were irradiated with ultraviolet light under the same conditions as above, except that the quartz glass was not fixed to the 96-well plate.

[0101] After 24 hours had passed since the UV irradiation, 10 μL of WST-8 reagent (manufactured by Dojin Chemical Co., Ltd.) was added to each well, and the wells were further cultured for 2 hours at 37° C. After the 2-hour culture, the absorbance at 450 nm was measured under the following conditions using a plate reader (device name: EnSpire, manufactured by PerkinElmer), and the average absorbance in the four wells (hereinafter also referred to as "measured absorbance") was calculated. FLASH: 100 times Measurement height: 7.5mm

[0102] The absorbance at 450 nm (hereinafter also referred to as "reference absorbance") when cultured under the same conditions as the control (without quartz glass) except for not irradiating ultraviolet light was set as the relative cell number of 100, and the relative cell number was calculated according to the following formula (I). The results are shown in Tables 2a, 2b, and 2c. Relative cell number = (measured absorbance / reference absorbance) × 100 (I)

[0103] [Table 2a] [Table 2b] [Table 2c]

[0104] As shown in Tables 2a, 2b, and 2c, the relative cell count was 96 or more when ultraviolet light was irradiated through the quartz glass of Example 4, whereas the relative cell count was 64 or less when ultraviolet light was irradiated through the quartz glass of Comparative Example 3. From this result, it was understood that the quartz glass of Example 4 can reduce the impact of ultraviolet light passing through the glass on living organisms, compared to the quartz glass of Comparative Example 3.

[0105] (UV irradiation test with a peak wavelength of 222 nm on Staphylococcus aureus) A medium (hereinafter simply referred to as the "medium") was prepared by dissolving hypopeptone (Shioya MS), dry yeast extract (Nacalai Tesque), and magnesium sulfate (Fujifilm Wako Pure Chemical Industries, Ltd.) in ultrapure water to have the same composition as NBRC (National Institute of Technology and Evaluation, Biotechnology Center) medium No. 702, and sterilizing it by autoclaving. In this test, this medium was used to culture Staphylococcus aureus.

[0106] Vial-dried Staphylococcus aureus (NBRC12732) was suspended in a medium, and then 15% agar powder (Fujifilm Wako Pure Chemical Industries, Ltd.) was added to the medium. This was spread on a plate and cultured at room temperature (24°C). Every four days, multiple colonies were scraped off the plate at once to prepare a bacterial suspension, and the bacteria were subcultured by spreading it on a new plate.

[0107] Staphylococcus aureus cultured as described above was inoculated at different concentrations into a 50 mL tube containing 10 mL of medium, and cultured overnight at 24°C with shaking. After overnight penetration culture, the bacterial cell liquid with an OD (optical density) 600nm of less than 1 was diluted with medium to obtain a bacterial cell liquid with an OD600nm of 0.2. The bacterial cell liquid with an OD600nm of 0.2 was further diluted 1000 times with medium to prepare a test liquid. 3 mL / well of agar medium was added to a 12-well plate, and the plate was opened and dried for 1 hour. After drying for 1 hour, 50 μL / well of the test liquid was added, and the plate was quickly shaken horizontally to diffuse the test liquid throughout the wells before the test liquid penetrated the agar.

[0108] Quartz glass (thickness 3.0 mm) of each Example and Comparative Example was placed on the well, and an ultraviolet irradiation device (excimer spot lamp, manufactured by Oak Seisakusho) was placed so that the distance from the agar surface to the irradiation surface was 30 mm, and ultraviolet light with a peak wavelength of 222 nm was irradiated so that the ultraviolet light that passed through the quartz glass was irradiated onto Staphylococcus aureus. The ultraviolet light irradiation was performed in a clean bench with the lid of the 12-well plate removed, and two conditions with different irradiation doses (10 J / cm 2 , or 20 mJ / cm 2As a control, Staphylococcus aureus was irradiated with ultraviolet light under the same conditions as above, except that no quartz glass was placed on the 12-well plate.

[0109] After 48 hours had elapsed since the UV irradiation, the UV irradiation was stopped and the number of colonies in the wells was counted, and the average number of colonies in the three wells (hereinafter also referred to as "measured colony number") was calculated.

[0110] As a reference example, the number of colonies measured without UV irradiation was determined. In the reference example, 1 / 50 of the amount of test solution (1 μL of test solution) added to the 12-well plate by the above method was diluted with 99 μL of medium to obtain a total of 100 μL of test solution, which was added to two 90 mm petri dishes containing 10 mL of agar medium, and cultured for 48 hours. After 48 hours of culture, the number of colonies in the two petri dishes was counted, and the average value was multiplied by 50 to obtain the number of colonies measured without UV irradiation (the number of colonies measured in the reference example).

[0111] The results are shown in Tables 3a and 3b below. [Table 3a] [Table 3b]

[0112] As shown in Tables 3a and 3b, the number of colonies measured when ultraviolet light was irradiated through the quartz glass of Example 4 was 0.1 [pieces / well], whereas the number of colonies measured when ultraviolet light was not irradiated (the number of colonies measured in the Reference Example) was 12700 [pieces / well]. From this result, it was understood that the quartz glass of Example 4 can be sterilized by ultraviolet light passing through it.

Claims

1. A quartz glass having a tin content of 5 ppm or more and 150 ppm or less, and a ratio of an absorption coefficient at a wavelength of 252 nm to an absorption coefficient at a wavelength of 222 nm of 2.5 or more.

2. 2. The quartz glass according to claim 1, which has an internal linear transmittance of 70% or less for light having a wavelength of 252 nm when the quartz glass has a thickness of 1 mm.

3. 3. The quartz glass according to claim 1, which has an internal linear transmittance of 30% or more for light having a wavelength of 222 nm when the quartz glass has a thickness of 1 mm.

4. 3. The quartz glass according to claim 1, wherein the internal linear transmittance of light having a wavelength of 222 nm at a thickness of 1 mm is higher than the internal linear transmittance of light having a wavelength of 252 nm at a thickness of 1 mm.

5. The absorption coefficient at a wavelength of 252 nm is 30,000 cm －１ The quartz glass according to claim 1 or 2.

6. The absorption coefficient at a wavelength of 222 nm is 200,000 cm －１ The quartz glass according to claim 1 or 2, wherein:

7. a first heat treatment step of heat-treating a raw material composition containing a silica source and a tin source at a temperature of 20° C. or higher and 1900° C. or lower under a vacuum of 10 Pa or lower; a second heat treatment step of heat treating the raw material composition heat-treated in the first heat treatment step under a nitrogen atmosphere at 1400° C. or more and 1900° C. or less; The method for producing quartz glass according to claim 1 or 2, comprising:

8. The method for producing quartz glass according to claim 7, wherein the silica source is silica powder.

9. 8. The method for producing silica glass according to claim 7, wherein the silica source is a silica powder obtained by hydrolysis of a silicon alkoxide.