Glass article and method of making the same

Abstract

The invention relates to a method of manufacturing a glass article and to a glass article having SiO2-rich glassy spheres with a low content of compositional inhomogeneity.

Description

Technical Field

[0001] This invention relates to a method for producing alumina-containing silicate glass articles, which in particular have a low alkali content and a low risk of breakage even under extreme temperature changes. The method includes a thermoforming step, which preferably includes drawing the glass. Glass articles produced using the method of this invention are characterized by having a very low content of compositionally inhomogeneous, SiO2-rich glassy spheres. Background Technology

[0002] A typical defect that can occur in glass products is the formation of non-uniform glass spheres. These spheres are a portion of the glass matrix with a different composition and refractive index than the rest of the glass matrix. Typically, such spheres may initially form around a piece of crystalline material, possibly due to incomplete melting. The dissolution of the crystalline material can take a long time, and the melting time may not be sufficient to complete the melting process and form a homogeneous glass matrix. Although this crystalline material may eventually dissolve during melting, the matrix may still have localized variations in glass composition. Therefore, the coefficient of thermal expansion of the non-uniform glass spheres may differ from that of the surrounding glass matrix.

[0003] Therefore, because the non-uniformly composed glass spheres create regions of tensile stress within the matrix, they may cause glass products to crack. The risk of cracking is even higher if the difference in thermal expansion between the glass matrix and the glass spheres is significant.

[0004] Furthermore, non-uniform glass spheres can also be detrimental below the fracture level, particularly for optical reasons. For aesthetic reasons, especially in very expensive products associated with specific aesthetic expectations, non-uniform glass spheres may simply be disliked. Moreover, non-uniform glass spheres can also impair the optical performance of glass articles requiring uniform optical properties during use. For example, non-uniform glass spheres are particularly disadvantageous in glass articles used in photomultiplier tubes because the spheres can cause scattering and / or absorption events, reducing the number of photons traveling along the intended optical path.

[0005] There is a need for glass products that have a low risk of breakage even when subjected to extreme temperature changes, such as those used as lampshades or as pharmaceutical packaging materials suitable for autoclaving. Furthermore, depending on the type of lamp, these glass products should also possess a chemically inert surface and high transparency, including in the UV region. A method for manufacturing such glass products is also required. Summary of the Invention

[0006] In the context of this application, non-uniform glassy spheres (hereinafter referred to as "GCI spheres") should be understood to include not only spherical shapes, but also, in particular, elliptical and near-spherical shapes with aspect ratios up to 2:1. However, they do not explicitly imply the inclusion of striations. Depending on the composition of the glass matrix, GCI spheres are primarily, but not exclusively, found near the surface of glass articles. They are typically transparent. Moreover, because their refractive index differs from that of the surrounding glass matrix, they are visible in transmitted light. Here, "transparent" means that the transmittance of light is at least 70% (measured at a thickness of 1 mm) across the entire visible light range (380 nm to 740 nm). This does not imply that the thickness of the glass or GCI sphere is limited to 1 mm; the thickness is merely a reference thickness for transmittance values. The size of the GCI sphere (measured at its maximum diameter) can be greater than 0.2 mm. In particular, the size can be greater than 0.3 mm, greater than 0.4 mm, or greater than 0.5 mm. Preferably, the size is in the range of 0.2mm-0.5mm, 0.3mm-0.6mm, 0.4mm-0.7mm, or 0.5mm-0.8mm.

[0007] We have found that in alumina-containing silicate glasses, the local glass composition within GCI spheres is typically dominated by SiO2. The SiO2 content within the GCI spheres can be increased by at least 15% by weight, or approximately 18-25% by weight, compared to the SiO2 content in the surrounding matrix. Therefore, this specification generally refers to SiO2-rich GCI spheres. At temperatures above 1470°C, SiO2 will form cristobalite, a polymorph of high-temperature silica minerals. During melting, the cristobalite particles dissolve very slowly. Therefore, if the processing temperature is high enough to dissolve the cristobalite particles quickly, GCI spheres may not be a problem in glasses with very high processing temperatures (such as some aluminosilicate glasses). Other glasses cannot melt at very high temperatures because volatile components may evaporate from the glass matrix.

[0008] The dissolution of cristobalite may involve the migration of alkali metal ions that form a eutectic mixture with SiO2. Therefore, if the alkali metal oxide content in the glass matrix is ​​low, cristobalite dissolves more slowly. Furthermore, the glass matrix surrounding the dissolving (or already dissolved) cristobalite particles may have a relatively large coefficient of thermal expansion, comparable to that of alkali metal silicate glasses. This explains why they form regions of tensile stress within the matrix.

[0009] Typically, depending on the composition of the glass matrix, we find that the SiO2 content within GCI spheres ranges from 75 wt% to 99.5 wt%. It can be at least 75 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or at least 75 wt%. It can be at most 99.5 wt%, at most 99 wt%, at most 98 wt%, at most 97 wt%, at most 96 wt%, or at most 95 wt%. The local concentration of SiO2 within a SiO2-rich GCI sphere may decrease from the core to the surface. If this is the case, then the concentrations mentioned above refer to the average concentration across the entire GCI sphere.

[0010] The coefficient of thermal expansion (CTE) is the average linear coefficient of thermal expansion over a temperature range of 20°C to 300°C. It is determined according to DIN ISO 7991:1987. In the glass industry, pure SiO2 glass has an extreme CTE of approximately 0.5 ppm / K. Therefore, SiO2-rich GCI spheres can also have a CTE as low as approximately 0.5 ppm / K. To avoid increased thermal tensile stress, the CTE of the glass matrix can be limited so that its CTE is no more than 10.0 times, 9.0 times, 8.0 times, 7.0 times, or 6.0 times greater than that of the GCI spheres.

[0011] This invention provides a production method that uses a special alumina source as a glass component, thereby specifically solving the problem of reduced stability of glass products due to the presence of GCI spheres.

[0012] In one aspect, the present invention relates to a method for manufacturing a glass article having an alumina-containing silicate glass matrix, preferably having a content of at least 0.75 W·m -1 ·K -1 The thermal conductivity, the method includes:

[0013] - Provide raw material blanks, including alumina source and SiO2 source;

[0014] - Melt the billet to a temperature exceeding 1500°C for no less than 3 hours;

[0015] - Molded glass products;

[0016] - Cool the glass article to room temperature;

[0017] The alumina source is gibbsite, and the glass matrix of the cooled glass product contains less than one SiO2-rich glass sphere per 15g of glass with uneven composition.

[0018] The thermal conductivity of the glass matrix (at 90℃) (λ) wIt can be at least 0.75 W·m -1 ·K -1 At least 0.80 W·m -1 ·K -1 At least 0.90 W·m -1 ·K -1 At least 0.92 W·m -1 ·K -1 At least 0.94 W·m -1 ·K -1 Or at least 0.96 W·m -1 ·K -1 The thermal conductivity of the glass matrix can be up to 1.4 W·m. -1 ·K -1 At most 1.35 W·m -1 ·K -1 At most 1.3 W·m -1 ·K -1 At most 1.25 W·m -1 ·K -1 At most 1.2 W·m -1 ·K -1 At most 1.18 W·m -1 ·K -1 At most 1.16 W·m -1 ·K -1 At most 1.14 W·m -1 ·K -1 At most 1.12 W·m -1 ·K -1 Or at most 1.1 W·m -1 ·K -1 In a preferred embodiment, because the number of GCI spheres, which typically have less favorable thermal conductivity, is small, the thermal conductivity of the glass article is within the same range. Thermal conductivity (λ) w According to ASTM E1461:2013, the thermal diffusivity (α) and specific heat capacity (c) are determined. p ) and density The product of:

[0019]

[0020] Thermal diffusivity (α) was determined according to ASTM E1461:2013 using a laser flash method with a xenon flash lamp on a cylindrical sample with a thickness of 1.0 mm and a diameter of 12.7 mm. Parameterization was performed using the Maier-Kelley method and a computational model of a transparent sample with pulse correction. Specific heat capacity (c) pDensity was determined according to DIN 51007:2019-04 by differential scanning calorimetry (DSC) (two separate samples, the first sample at 28℃-400℃ and the second sample at 28℃-550℃, heated at a rate of 10 K / min in an argon atmosphere, sample size approximately 90 mg). The density was determined by buoyancy according to ASTM C 693:1993 (modified by adding a surfactant to the water), where the temperature dependence of density was calculated according to DIN ISO 7991:1998-02 (sample: a cylindrical rod 100 mm long and 5 mm in diameter, temperature range: 25 °C-425 °C, rate: 2 K / min).

[0021] Gibbsite, also known as gibbsite or diaspore, is one of the four mineral forms of aluminum hydroxide, Al(OH)3. Its chemical formula is usually also represented as γ-Al(OH)3. Rock bauxite contains gibbsite as one of its three main phases and is the most common source of gibbsite.

[0022] Surprisingly, it was found that if gibbsite is used as the alumina source in the raw materials for glass (especially glass with a very low coefficient of thermal expansion), the content of GCI spheres in glass products can be reduced very effectively. Even with low alkali metal oxide content and melting temperatures exceeding 1500°C, it is still possible to achieve a content of less than one SiO2-rich GCI sphere. Therefore, glass products produced by this method exhibit excellent thermal stability, making them particularly suitable for lampshades or autoclaved pharmaceutical packaging materials.

[0023] Unwilling to be bound by theory, the inventors believe that the aluminum hydroxide in gibbsite improves the dissolution of residual cristobalite particles. During the melting process of this aluminosilicate glass, excess SiO2 exists, which cannot find network ligands and is therefore not included in the network. Clearly, gibbsite promotes the formation of a SiO2-rich network within the glass matrix. Therefore, the residual cristobalite particles dissolve more effectively.

[0024] Glass manufacturers often attempt to reduce the content of certain IR-absorbing components (such as Ti, Fe, or H₂O). This results in glass with a relatively low specific heat capacity and a high thermal conductivity. For example, glass produced according to the present invention can have a specific heat capacity of at least 0.75 W·m⁻¹. -1 ·K -1The thermal conductivity of the glass is low. The glass melting tank used in glass production is heated by a burner. Therefore, a reduction in the amount of IR-active components will reduce the amount of heat the glass can absorb. If the burner exhibits irregular behavior or fluctuations, the glass temperature will drop rapidly. Consequently, these glasses are very difficult to handle in production because they are highly sensitive to temperature fluctuations that negatively impact the melting of the raw materials. The selected aluminum source improves processing characteristics and reduces the number of GCI spheres produced even when the glass contains small amounts of IR-absorbing components. In one embodiment, the glass may contain moderate amounts of Ti and / or Fe, which can at least partially improve the heat capacity and / or thermal conductivity.

[0025] Since the most common starting shape for glass articles used in lampshades and autoclaved pharmaceutical packaging materials is a tube, in some embodiments of the invention, the step of forming the glass article includes drawing a glass tube, optionally using the Danner tube drawing process.

[0026] The tube drawing process and the resulting tubes both benefit particularly from the method of the present invention, because the drawing process causes even more significant deformation of the GCI spheres in the glass. The more or less spherical cristobalite crystal particles initially formed during the melting process and the resulting spherical GCI spheres are stretched into more elongated elliptical or near-spherical shapes during the drawing process. However, the drawing process only deforms the GCI spheres without causing striations. In these cases, the aspect ratio of the shape can vary from approximately 1:1 to as high as approximately 2:1. Because the elongated inhomogeneities lie along the longitudinal axis of the tube, the tensile stress generated in the matrix during thermal expansion or contraction processes is particularly critical for tube breakage. Therefore, if the forming of glass articles involves a drawing process, the quality and scrap rate of the glass articles will particularly benefit from the method according to the invention. This is not limited to the Dana process, but also applies to other drawing methods similarly considered in this invention, such as the Vello drawing process or the A-drawing process (downward drawing process).

[0027] In some preferred embodiments, the average particle size D50 of the alumina source is 20 μm to 300 μm, preferably 20 μm to 150 μm, 25 μm to 140 μm, 30 μm to 120 μm, or 35 μm to 100 μm. Preferably, the average particle size D50 is at least 20 μm, at least 25 μm, at least 30 μm, at least 35 μm, or at least 40 μm. Preferably, the average particle size D50 is at most 90 μm, at most 100 μm, at most 110 μm, at most 120 μm, at most 130 μm, at most 140 μm, at most 150 μm, at most 175 μm, at most 200 μm, at most 225 μm, at most 250 μm, at most 275 μm, or at most 300 μm. Particle size D50 was determined according to ISO 13320:2020-1 using a laser diffraction particle analyzer (e.g., Microtrac X100) via dynamic light scattering. The advantage of this particle size distribution range has been demonstrated in that it represents the optimal range for handling, mixing, melting, and minimizing the impact on GCI spheres within the glass.

[0028] In some preferred embodiments, the alumina source has a viscosity of less than 5.0 μm, as measured according to DIN ISO 9277:2014-01. 2 / g BET surface area. Preferably, the BET surface area is less than 4.0m². 2 / g, less than 3.0m 2 / g, less than 2.0m 2 / g, less than 1.0m 2 / g, less than 0.5m 2 / g or less than 0.4m 2 / g. Preferably, the BET surface area is greater than 0.1m². 2 / g, greater than 0.15m 2 / g, greater than 0.2m 2 / g or greater than 0.25m 2 / g. BET surface area is also an indicator of particle porosity and pore size. While a larger surface area will promote particle dissolution and melting by increasing the contact surface, a smaller pore size will reduce the proximity of the melt to the particle surface. Therefore, there is an optimal value that should not be exceeded.

[0029] In some preferred embodiments, the density of the alumina source is less than 2.600 g / cm³. 3 Preferably, the density is less than 2.590 g / cm³. 3 Less than 2.580 g / cm³ 3 Less than 2.570 g / cm³ 3 Less than 2.560 g / cm³ 3 Less than 2.550 g / cm³ 3 Less than 2.540 g / cm³3 Or less than 2.530 g / cm³ 3 Lower density is characterized by a less perfect crystal structure. The more defects in the crystal lattice, the lower the energy level required for melting, and therefore the easier and faster the particles melt.

[0030] In the method according to the invention, preferably, the temperature of the melt does not exceed 1700°C. More preferably, the temperature of the melt does not exceed 1680°C, 1660°C, 1640°C, 1620°C, or 1600°C.

[0031] Preferably, the alumina source contains at least 0.015 wt% sodium (Na) (determined by atomic absorption spectrometry (AAS)). More preferably, the alumina source contains at least 0.03 wt% Na, at least 0.045 wt% Na, at least 0.06 wt% Na, at least 0.075 wt% Na, at least 0.1 wt% Na, at least 0.15 wt% Na, or at least 0.2 wt% Na. As mentioned above, defective lattices will benefit the melting process and promote melting. Therefore, because the aluminum source particles will melt more easily at lower temperatures, a certain amount of sodium impurities in the aluminum source can help reduce the number of GCI spheres in the glass.

[0032] In another aspect, the present invention relates to the use of gibbsite as an alumina source in the manufacture of glass articles having an alumina-containing silicate glass matrix.

[0033] In another aspect, the present invention relates to a glass article comprising an alumina-containing silicate glass matrix, wherein the glass matrix contains less than one compositionally non-uniform SiO2-rich glass sphere per 15g of glass. In one embodiment, the glass article contains less than one compositionally non-uniform SiO2-rich glass sphere per 25g, 50g, or 100g of glass.

[0034] In the embodiments, the glass article may have one or more SiO2-rich glass spheres with uneven composition per 1000g of glass, per 900g of glass, or per 800g of glass.

[0035] The aspect ratio of SiO2-rich GCI spheres in glass articles can be 1:1 to 1.1:1, 1:1 to 1.2:1, 1:1 to 1.3:1, 1:1 to 1.4:1, 1:1 to 1.5:1, 1:1 to 1.6:1, 1:1 to 1.7:1, 1:1 to 1.8:1, 1:1 to 1.9:1, or 1:1 to 2.0:1. The aspect ratio is preferably at least 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, or 1.9:1. The aspect ratio is preferably at most 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, or 2.0:1.

[0036] In some embodiments of the present invention, the glass matrix contains B2O3. Preferably, it contains 3.0 mol% or more, 4.0 mol% or more, 5.0 mol% or more, 6.0 mol% or more, 7.0 mol% or more, 8.0 mol% or more, 9.0 mol% or more, or 10.0 mol% or more.

[0037] In some preferred embodiments of the present invention, the glass matrix contains B2O3 in an amount greater than 15.0 mol%, greater than 16.0 mol%, greater than 17.0 mol%, greater than 18.0 mol%, greater than 19.0 mol%, or greater than 20.0 mol%.

[0038] In some preferred embodiments of the present invention, the glass matrix contains less than 12.0 mol% of alkali metal oxides. Preferably, the glass matrix contains less than 11.0 mol%, less than 10.0 mol%, or less than 9.0 mol% of alkali metal oxides.

[0039] In some embodiments of the present invention, the glass matrix has a coefficient of thermal expansion of less than 5.0 ppm / K. Preferably, the coefficient of thermal expansion is less than 4.5 ppm / K, less than 4.0 ppm / K, less than 3.5 ppm / K, or less than 3.0 ppm / K.

[0040] In another respect, the present invention relates to a glass article that can be obtained by the method according to the invention.

[0041] In a preferred embodiment, the glass article may be tubular.

[0042] In some embodiments of the invention, the glass article has a UV transmittance of at least 60% at 200 nm and / or at wavelengths [λ] of at least 83% (measured at a thickness of 1 mm). At wavelengths [λ] of at 254 nm, 280 nm and / or 310 nm, the UV transmittance may be at least 86% or at least 88%. This does not mean that the thickness of the glass is limited to 1 mm; this thickness is only a reference thickness for the transmittance value.

[0043] In some embodiments of the present invention, the glass article is at least 10 cm at 254 nm and / or 200 nm. 2 The maximum UV transmittance deviation over the area of ​​the glass article is not more than 5.0%, not more than 3.0%, or not more than 1.0%. This maximum deviation can be measured by determining the UV transmittance over the area of ​​the glass article and calculating the difference between the maximum and minimum values.

[0044] In another aspect, the present invention relates to a group of glass articles comprising 5 to 5000 glass articles. The group may include at least 10, 30, 50, 70, 90, 100, 150, 200, 250, or 500 glass articles. The group may also include up to 4500, 4000, 3500, 3000, 2500, 2000, 1500, or 1000 glass articles. Glass articles used in medical packaging and lamps or sensors are typically used in groups with the desired uniformity of properties within the group. Using the method of the present invention, such groups of glass articles with very low property variation can be produced. In particular, groups of glass articles with good optical transmission properties, transparency, and mechanical stability under thermal stress can be produced.

[0045] Glass composition

[0046] The glass is preferably borosilicate glass. In one design, the borosilicate glass comprises the following components (based on mol% of oxides):

[0047] <![CDATA[SiO2]]> 60-78 <![CDATA[Al2O3]]> 1.0-10 <![CDATA[B2O3]]> 12-24 <![CDATA[Li2O]]> 0-3.0 <![CDATA[Na2O]]> 0-6 <![CDATA[K2O]]> 0-4 MgO 0-6 CaO 0-6 SrO 0-4 BaO 0-4 <![CDATA[F - ]]> 0-6 <![CDATA[Cl - ]]> 0-0.5 <![CDATA[R2O]]> 3.5-10 RO 0-6

[0048] The glass of this invention may contain at least 60 mol% SiO2. SiO2 contributes to the glass's hydrolysis resistance and transparency. If the SiO2 content is too high, the glass's melting point becomes too high. Temperatures T4 and Tg also rise sharply. Therefore, the SiO2 content should be limited to a maximum of 78 mol%.

[0049] Preferably, the SiO2 content is at least 61 mol%, at least 63 mol%, or at least 65 mol%. The content can be limited to a maximum of 75 mol% or a maximum of 72 mol%.

[0050] The glass of the present invention contains a maximum proportion of 10 mol% Al2O3. Al2O3 contributes to the segregation stability of the glass, but a larger proportion reduces acid resistance. Furthermore, Al2O3 increases the melting temperature and T4. Therefore, the content of this component should be limited to a maximum of 9 mol% or a maximum of 8 mol%. In some embodiments, Al2O3 is used in a smaller proportion of at least 1.0 mol%, at least 1.5 mol%, at least 2 mol%, at least 2.5 mol%, or at least 3 mol%, or at least 3.5 mol%.

[0051] The glass of the present invention may contain at least 12 mol% B2O3. B2O3 has a beneficial effect on the melting properties of the glass, particularly by lowering the melting temperature, and allowing the glass to fuse with other materials at lower temperatures. However, the amount of B2O3 should not be too high, otherwise the glass will have a strong tendency to segregate. Therefore, the B2O3 content should be limited to up to 24 mol%, up to 22 mol%, or up to 20 mol%. In some forms, the B2O3 content is at most 17 mol%. The B2O3 content may be at least 12 mol% or at least 14 mol%.

[0052] In a preferred design, the ratio of the sum of the contents of B2O3, R2O, and RO (in mol%) to the sum of the contents of SiO2 and Al2O3 (in mol%) is at most 0.4, particularly at most 0.35, and more preferably at most 0.33. In one embodiment, this value is at least 0.1, preferably at least 0.2, or at least 0.26. Glasses with the above proportions exhibit good properties in terms of hydrolysis resistance and segregation factor, and they also have low induced extinction rates, which have many advantages, especially when used as UV-transparent materials.

[0053] The glass of the present invention may contain up to 3.0 mol%, up to 2.8 mol%, or up to 2.5 mol% of Li₂O. Li₂O increases the fumigability of the glass and results in a beneficial shift from the UV edge to lower wavelengths. However, lithium oxide is prone to evaporation, increasing the tendency for segregation and also raising the price of the mixture. In a preferred design, the glass contains only a small amount of Li₂O, for example, up to 3.0 mol%, up to 2.0 mol%, or up to 1.9 mol%, or the glass contains no Li₂O.

[0054] The glass of the present invention contains up to 6 mol% Na₂O. Na₂O increases the fusibility of the glass. However, sodium oxide also leads to a decrease in UV transmittance and an increase in the coefficient of thermal expansion. The glass may contain at least 1 mol% or at least 2 mol% Na₂O. In one variation, the Na₂O content is at most 5 mol% or at most 4 mol%.

[0055] The glass of this invention contains a maximum of 4 mol% K₂O. K₂O increases the glass's fuseability and results in a beneficial shift from the UV edge to lower wavelengths. Its content can be at least 0.3 mol% or at least 0.75 mol%. However, excessively high potassium oxide content can cause the glass to be unsuitable for use in photomultiplier tubes due to its isotopic composition. 40 K exhibits interference effects due to its radiation characteristics. Therefore, the content of this component must be limited to a maximum of 3 mol% or a maximum of 2 mol%.

[0056] In embodiments of the invention, the ratio of Na₂O to K₂O content (in mol%) is at least 1.5, particularly at least 2. In embodiments of the invention, the ratio is at most 4, particularly at most 3. Both oxides are used to improve the fusing properties of the glass. However, using too much Na₂O will reduce UV transmittance. Too much K₂O will increase the coefficient of thermal expansion. We have found that a given ratio achieves the best results, i.e., both UV transmittance and the coefficient of thermal expansion are within a favorable range.

[0057] The amount of R2O in the glass of the present invention is preferably no more than 10 mol%, no more than 8 mol%, or no more than 7 mol%. The glass may contain at least 3.5 mol%, at least 4 mol%, or at least 4.5 mol% of R2O. Alkali metal oxides improve the solubility of the glass; however, as mentioned above, higher proportions can lead to various disadvantages.

[0058] The glass of this invention may contain up to 4 mol% or up to 2 mol% MgO. MgO is beneficial for fuselability, but at higher proportions, it has been shown to cause problems with UV transmittance and segregation tendency. A preferred design is MgO-free.

[0059] The glass of the present invention may contain up to 4 mol% or up to 2 mol% CaO. CaO is beneficial for fuselability, but at higher proportions, it has been shown to be problematic in terms of UV transmittance. Preferred forms contain no CaO or only a small amount of CaO, for example, at least 0.1 mol%, at least 0.3 mol%, or at least 0.5 mol%.

[0060] The glass of the present invention may contain up to 4 mol%, up to 1 mol%, or up to 0.5 mol% SrO. SrO is beneficial for fuselability, but at higher proportions, it has been shown to be problematic in terms of UV transmittance. A preferred design is SrO-free.

[0061] The glass of the present invention may contain up to 4 mol% or up to 2 mol% BaO. BaO leads to improved hydrolysis resistance. However, excessively high barium oxide content can cause segregation, resulting in glass instability. Preferred embodiments contain at least 0.1 mol%, at least 0.3 mol%, or at least 0.8 mol% BaO.

[0062] It has been shown that alkaline earth metal oxides (RO) have a significant influence on segregation tendency. Therefore, in a design form, special attention must be paid to the content of these components and the relationships between them. Thus, the ratio of BaO (mol%) to the sum of MgO, SrO, and CaO (mol%) should be at least 0.4. Preferably, this value is at least 0.55, at least 0.7, or at least 1.0. In a particularly preferred form, this value is at least 1.5 or even at least 2. Compared to other alkaline earth metal oxides, BaO has the greatest advantage in terms of segregation and hydrolysis resistance. However, this ratio should not exceed 4.0 or 3.0. In an advantageous form, the glass contains at least a small amount of CaO and BaO and is free of MgO and SrO.

[0063] Advantageous properties are particularly obtained when the ratio of CaO to BaO (in mol%) in the glass is less than 2.0. In particular, this ratio should be less than 1.5 or less than 1.0. The optimal ratio is even lower, particularly less than 0.8 or less than 0.6, and in preferred designs, the ratio is at least 0.3.

[0064] In one variation, the mol% ratio of B₂O₃ to BaO in the glass is at least 8 and at most 20. Preferably, this ratio is at least 10 or at least 11, and in preferred designs, the ratio is limited to a maximum of 18, 16, 15, or 13. In particular, the ratio is not less than 10 and not more than 15, or not less than 11 and not more than 13; glasses with the above ratios exhibit good properties in terms of hydrolysis resistance and segregation factor, as well as low induced absorbance.

[0065] The RO content in the glass of this invention can be at least 0.3 mol%. Alkali earth metal oxides are beneficial for fuselability, but at higher proportions, they have proven problematic in terms of UV transmittance. In one variant, the glass contains a maximum of 3 mol% RO.

[0066] The sum of the contents of alkaline earth metal oxides and alkali metal oxides RO+R2O, expressed in mol%, can be limited to a maximum of 10 mol%. An advantageous design may contain a maximum of 9 mol% of these components. Preferably, the contents of these oxides are at least 4 mol%, at least 5 mol%, or at least 6 mol%. Excessive proportions of these components can increase segregation tendency and reduce the glass's resistance to hydrolysis.

[0067] The ratio of the B₂O₃ content (in mol%) to the sum of the R₂O and RO contents (in mol%) can be at least 1.3, at least 1.5, or at least 1.8. This ratio can be limited to a maximum of 6, a maximum of 4.5, or a maximum of 3. If there is an excessive amount of alkali metal or alkaline earth metal oxides relative to B₂O₃, alkali metal or alkaline earth metal borates will form during glass segregation. Adjusting the above ratio has proven advantageous.

[0068] To ensure that melting characteristics, including Tg and T4, are within the desired range, it may be advantageous to set the ratio of the B2O3 content (in mol%) to the sum of the SiO2 and Al2O3 contents (in mol%) within a narrow range. In an advantageous design, this ratio is at least 0.15 and / or at most 0.4.

[0069] The ratio of the total alkali metal oxide R₂O to the total alkaline earth metal oxide RO, expressed in mol%, is preferably >1, particularly >1.1, or >2. In one design configuration, this ratio is at most 10, at most 7, or at most 5.

[0070] The glass of this invention may contain 0-6 mol% F. - Preferably, F - The content is at most 4 mol%. In one design, at least 1 mol% or at least 2 mol% of this component is used. Component F - It improves the glass's fusibility and affects the UV edge orientation towards smaller wavelengths.

[0071] The glass of the present invention may contain less than 1 mol%, particularly less than 0.5 mol% or less than 0.3 mol% Cl. - The appropriate lower limit is 0.01 mol% or 0.05 mol%.

[0072] As previously mentioned, the glass may contain moderate amounts of IR-absorbing compounds, such as Fe and Ti, to improve melting. The glass of the present invention may contain Fe₂O₃ in amounts of 1 ppb to 10 ppm, 10 ppb to 9 ppm, 20 ppb to 8 ppm, 30 ppb to 7 ppm, 40 ppb to 6 ppm, or 50 ppb to 5 ppm. The amount of Fe₂O₃ may be at least 1 ppb, at least 10 ppb, at least 20 ppb, at least 30 ppb, at least 40 ppb, or at least 50 ppb. The amount of Fe₂O₃ may be at most 10 ppm, at most 9 ppm, at most 8 ppm, at most 7 ppm, at most 6 ppm, or at most 5 ppm.

[0073] The glass of the present invention may contain TiO2 in amounts of 1 ppb to 10 ppm, 10 ppb to 9 ppm, 20 ppb to 8 ppm, 30 ppb to 7 ppm, 40 ppb to 6 ppm, or 50 ppb to 5 ppm. The amount of TiO2 may be at least 1 ppb, at least 10 ppb, at least 20 ppb, at least 30 ppb, at least 40 ppb, or at least 50 ppb. The amount of TiO2 may be at most 10 ppm, at most 9 ppm, at most 8 ppm, at most 7 ppm, at most 6 ppm, or at most 5 ppm.

[0074] When the description states that the glass is free of a component or does not contain a certain component, it means that the component may exist at most as an impurity. This means that it will not be added in large quantities. "Not large quantities" is an amount less than 0.5 ppm, preferably less than 0.25 ppm, and most preferably less than 0.125 ppm.

[0075] In one embodiment, the glass contains less than 3.5 ppm, particularly less than 2.5 ppm or less than 1.0 ppm of arsenic. Glass containing less than 3.5 ppm, less than 2.5 ppm, or less than 1.0 ppm of antimony is preferred. Besides their negative impacts on UV transmittance and sunlight exposure, arsenic and antimony are also toxic and hazardous to the environment and should be avoided.

[0076] In a particularly preferred design, the borosilicate glass comprises the following components (based on mol% of oxides):

[0077] <![CDATA[SiO2]]> 68-73 <![CDATA[Al2O3]]> 2-5 <![CDATA[B2O3]]> 12-18 <![CDATA[Na2O]]> 1-4 <![CDATA[K2O]]> 0-2 CaO >0-2 SrO 0-1 BaO 0-4 <![CDATA[F - ]]> 0-6

[0078] In another particularly preferred form, the glass comprises the following components in mol% terms:

[0079]

[0080]

[0081] Products

[0082] In one embodiment, the thickness of the glass article, particularly the wall thickness in the case of a glass tube, can be at least 0.1 mm or at least 0.3 mm. The thickness can be limited to up to 3 mm or up to 2 mm. The outer diameter of the glass article, such as the outer diameter of a glass tube or glass rod, can be up to 50 mm, up to 40 mm, or up to 30 mm. The outer diameter can particularly be at least 1 mm, at least 2 mm, or at least 3 mm. In one embodiment, the article has a thickness of at least 3 mm and / or at most 20 mm. Optionally, the thickness is at least 5 mm, at least 6 mm, or at least 8 mm. The thickness can be limited to a maximum of 20 mm, up to 16 mm, up to 14 mm, or up to 12 mm. In one embodiment, the article has a length and a width, particularly a length greater than the width. The length can be at least 20 mm, at least 40 mm, or at least 60 mm. Optionally, the length can be up to 1000 mm, up to 600 mm, up to 250 mm, or up to 120 mm. Preferably, the length is 20mm to 1000mm, 40mm to 600mm, or 60mm to 250mm. The width can be at least 10mm, at least 25mm, or at least 35mm. Optionally, the width is at most 575mm, at most 225mm, or at most 110mm. Preferably, the width is 10mm to 575mm, 25mm to 225mm, or 35mm to 110mm. In a preferred embodiment, the article is in the form of a sheet or a disc.

[0083] In one aspect, the present invention relates to a glass article comprising or composed of the glass described herein. In one embodiment, the glass article has at least one polished surface. Optionally, the glass article has at least one chamfered edge. The surface roughness Ra of the polished surface may be less than 10 nm or less than 5 nm. The chamfered edge is more impact-resistant, particularly more resistant to shattering than a non-chamfered edge.

[0084] Heat tempering and / or chemical tempering

[0085] Optionally, the manufacturing process includes chemical tempering and / or hardening steps for the glass articles. "Tempering" is also known as "hardening" or "toughening".

[0086] Preferably, the glass article is tempered on at least one surface, particularly by thermal tempering and / or chemical tempering. For example, the glass article can be chemically tempered by ion exchange. In this process, smaller alkali ions in the article are typically replaced by larger alkali ions. Typically, smaller sodium ions are replaced by potassium ions. However, very small lithium ions may also be replaced by sodium and / or potassium ions. Optionally, alkali ions can be replaced by silver ions. Another possibility is that alkaline earth ions exchange with each other according to the same principle as alkali ions. Preferably, the ion exchange is carried out in a molten salt bath between the article surface and the salt bath. Pure molten salts, such as molten KNO3, can be used for exchange. However, salt mixtures or mixtures of salts with other components can also be used. The mechanical resistance of the article can be further increased if a selectively tuned compressive stress distribution is established within the article. This can be achieved through a single-stage ion exchange process or a multi-stage ion exchange process.

[0087] Compressive stress is generated in the corresponding region by replacing small ions with large ions or by heat tempering, and this compressive stress decreases from the surface of the glass product towards the center. The maximum compressive stress is located just below the glass surface and is also called compressive stress (CS). CS is stress, expressed in MPa. The depth of the compressive stress layer is simply referred to as "DoL" and is measured in μm. Preferably, CS and DoL are measured using an FSM-60LE instrument from Orihara.

[0088] In one embodiment, CS is greater than 100 MPa. More preferably, CS is at least 200 MPa, at least 250 MPa, or at least 300 MPa. More preferably, CS is at most 1000 MPa, at most 800 MPa, at most 600 MPa, or at most 500 MPa. Preferably, CS is in the range of >100 MPa to 1000 MPa, 200 MPa to 800 MPa, 250 MPa to 600 MPa, or 300 MPa to 500 MPa.

[0089] In one embodiment, the glass article is heat-tempered. Heat tempering is typically achieved by rapidly cooling the hot glass surface. Compared to chemical tempering, the advantage of heat tempering is that a deeper (larger DoL) compressive stress layer can be formed. This makes the glass less prone to scratches because the compressive stress layer is not as easily scratched through as a thinner compressive stress layer.

[0090] For example, glass or glass articles may undergo a heat tempering process after melting, forming, annealing / cooling, and cold post-processing steps. In this process, the glass body (e.g., the glass articles or primary products described previously), such as flat glass, is preferably fed horizontally or suspended in the apparatus and rapidly heated to the transformation temperature T. GThe above temperatures, with a maximum of 150°C, are then used, for example, by rapidly cooling the surface of the glass body through a nozzle system. Due to the rapid cooling of the glass surfaces, they are frozen in an expanding network, while the interior of the glass body cools slowly and has time to contract further. This generates compressive stress on the surface layer and tensile stress internally. The magnitude of the compressive stress depends on various glass parameters, such as CTE. 玻璃 (average linear thermal expansion coefficient below Tg), CTE 液体 (Average linear thermal expansion coefficient above Tg), strain point, softening point, Young's modulus, and information regarding heat transfer between the cooling medium and the glass surface, as well as the thickness of the glass body.

[0091] Preferably, a compressive stress of at least 50 MPa is generated. Therefore, the flexural strength of the glass body can be doubled to tripled compared to untempered glass. In one embodiment, the glass is heated to a temperature of 750°C to 800°C and rapidly tempered in a stream of cold air. Optionally, the blowing pressure can be from 1 kPa to 16 kPa. For the glass or glass articles described herein, compressive stress values ​​of, for example, 50 MPa to 250 MPa, particularly 75 MPa to 200 MPa, are achieved on commercially available systems.

[0092] In one embodiment, the glass article has a compressive stress layer, the compressive stress of which is at least 50 MPa, particularly at least 75 MPa, at least 85 MPa, or at least 100 MPa. The glass article may have the compressive stress layer on one, two, or all of its surfaces. The compressive stress of the compressive stress layer may be limited to a maximum of 250 MPa, a maximum of 200 MPa, a maximum of 160 MPa, or a maximum of 140 MPa. These compressive stress values ​​are particularly likely to be present in heat-tempered glass articles.

[0093] In one embodiment, the depth of the compressive stress layer of the glass article is at least 10 μm, at least 20 μm, at least 30 μm, or at least 50 μm. In some embodiments, the layer may even be at least 80 μm, at least 100 μm, or at least 150 μm. Optionally, the DoL is limited to at most 2000 μm, at most 1500 μm, at most 1250 μm, or at most 1000 μm. In particular, the DoL can be from 10 μm to 2000 μm, from 20 μm to 1500 μm, or from 30 μm to 1250 μm. In one embodiment, the glass article is heat-tempered, and its DoL is at least 300 μm, at least 400 μm, or at least 500 μm. Optionally, the DoL can be at most 2000 μm, at most 1500 μm, or at most 1250 μm. In one embodiment, DoL is 300 μm to 2000 μm, 400 μm to 1500 μm, or 500 μm to 1250 μm.

[0094] Example

[0095] This invention relates to glass that possesses resistance in several aspects. Particularly durable glass is especially useful when exposed to special conditions. This is, for example, in extreme environments. Extreme environments are special application areas requiring particular resistance, durability, and safety, such as areas requiring explosion protection.

[0096] In one embodiment, the present invention relates to a glass article particularly suitable for extreme environments. The article may be a sheet, disc, tube, rod, ingot, or block.

[0097] Optionally, the glass article comprises an alumina-containing silicate glass matrix, wherein each 15g of glass contains less than one compositionally inhomogeneous SiO2-rich glass sphere, and further, wherein the thickness of the glass article is at least 0.3mm, particularly at least 3mm and / or up to 20mm.

[0098] In extreme environments, providing a minimum thickness for glass products can be useful because thicker glass is mechanically more stable than thinner glass. However, thicker glass absorbs a larger portion of the UV radiation entering the glass, generating heat. In environments with highly flammable materials, this higher heat generation can be problematic. Glass products with lower induced extinction rates at 200 nm and / or 254 nm offer the advantage of maintaining high transmittance for the wavelength in question, even after prolonged use, while avoiding the generation of extreme heat.

[0099] According to the present invention, the glass article can also be used in a UV lamp for surface sterilization in extreme environments. In one embodiment, the glass article is used in a UV lamp (particularly as a lampshade) for sterilizing the target area. The target area can be an object touched by many people, such as a handle, particularly a door handle. For example, the UV lamp can be aligned in such a way that it applies UV radiation to the target area. In this case, some degree of proximity to the target area is unavoidable. Therefore, there is a risk that the glass article will be damaged by impact. This necessitates the need for mechanical resistance. The mechanical resistance can be improved by increasing the thickness of the glass article; however, this reduces the transmittance of the article and results in more intense heating of the glass during UV lamp operation. Overheating should be avoided, which in turn is positively influenced by the very good transmittance and low induced extinction rate. Excessive temperature compromises safety due to the risk of user burns or explosions. In principle, the risk of burns can be reduced by increasing the distance, but this must be compensated for by using greater radiation intensity, which in turn has the disadvantage of generating more heat.

[0100] This invention also relates to the use of a UV lamp and glass articles in a UV lamp for disinfection, particularly in extreme environments, and especially for disinfecting contact surfaces (e.g., those touched by many people). Maintaining a minimum distance of 5 cm, particularly 7.5 cm or 10 cm, between the surface to be disinfected and the glass article has proven advantageous. When using the glass article described herein, a minimum power of 1.0 mW / cm² can be applied to the contact surface. 2 At least 1.5mW / cm 2 At least 2.5mW / cm 2 At least 3.0mW / cm 2 Or at least 3.5 mW / cm 2 The power density is [specific value]. The target area is the surface to be disinfected. Optionally, the power density is up to 20 mW / cm². 2 At most 15mW / cm 2 Or at most 10mW / cm 2 Specifically, power density is the power of UV radiation, particularly UV-C radiation, mediated by a UV lamp, that can be measured at the site of application. Preferably, the site of application is disinfected periodically. This means that the site is not continuously irradiated, but rather intermittently irradiated. For example, the irradiation interval can be triggered by a user touch or actuation. For example, the irradiation interval can be at least 1 second, at least 5 seconds, at least 10 seconds, or at least 20 seconds. Optionally, the irradiation interval can last for up to 10 minutes, up to 5 minutes, up to 2 minutes, or up to 1 minute.

[0101] In one embodiment, the UV lamp and / or glass article have a thermally optimized structure, wherein the thickness of the glass article and the UV transmittance of the glass article are selected in such a way that when using 120 W / cm, an arc length of 4 cm (e.g., Philips HOK 4 / 120), and a UVC power density of 17.27 mW / cm², the UV lamp and / or glass article have a thermally optimized structure. 2When a medium-pressure mercury lamp irradiates a portion of the glass article at a distance of 70 mm from the article (opposite to the light source) for 5 seconds at an ambient temperature of 20°C, the temperature of the surface of the glass article facing the irradiated portion does not exceed 45°C. In one embodiment, the radiation passes perpendicularly through the glass article, i.e., the light enters the glass article substantially perpendicularly to the surface facing the light source and / or exits the glass article substantially perpendicularly to the surface facing the irradiated portion. Specifically, the temperature does not exceed values ​​of 42.5°C, 40°C, or 37.5°C. In one embodiment, even after irradiation for 10, 20, 30, 45, 60, 90, 120, 150, or 180 seconds, the temperature limit is not exceeded. This characteristic describes the intensity of heating of the glass article when vertically irradiated by a commonly used UV light source. A UV lamp with a lampshade made of glass article does not heat to a dangerous degree. UVC power density refers to the power density imparted by radiation within the UVC range (280 nm to 200 nm). Medium-pressure mercury lamps also emit light of other wavelengths, which are not considered when taking UVC power density into account. The measurements were performed under ambient atmosphere. It should be clarified that the described characteristics do not limit the use of UV lamps or glassware in medium-pressure mercury lamps.

[0102] In one embodiment, the glass article meets the requirements for fracture modes according to DIN EN 12150-1:2020-07. The entire article or a portion thereof can be examined; deviations from the specified standard, as long as they exceed the area to be considered, mean the article can be smaller than the dimensions shown herein. The area to be considered for the fracture mode can, in particular, be 40 mm × 40 mm or 25 mm × 25 mm. In one embodiment, the glass article breaks into not less than 25 pieces, particularly not less than 30 or not less than 40 pieces, under the above conditions. It is advantageous for the article to break into many pieces because, in the event of breakage, if the fragments are small, the risk of injury is lower. The fracture mode can be influenced, for example, by selecting the glass composition, cooling conditions (thermal shrinkage), by adjusting the stress in the glass, and / or by tempering the article.

[0103] In one embodiment, the present invention relates to a glass article comprising an alumina-containing silicate glass matrix, wherein each 15g of glass contains less than one compositionally inhomogeneous SiO2-rich vitreous sphere; further, wherein the thickness of the glass article is at least 0.3mm, particularly at least 3mm and / or up to 20mm; further, wherein the article has a compressive stress of at least 50MPa on at least one surface and has a fracture mode characterized by breaking into at least 25 pieces in an area of ​​40mm × 40mm as determined according to DIN EN 12150-1. Attached Figure Description

[0104] Figure 1 This is the DTA / TG curve of gibbsite and boehmite obtained from thermal analysis.

[0105] Figure 2 It is a graph showing the change of composition in a glass melt containing gibbsite over time.

[0106] Figure 3 Examples of GCI spheres in tubular form of alumina-containing silicate glass articles. Detailed Implementation

[0107] The melting characteristics of different aluminum raw materials were compared by differential thermal analysis / thermogravimetric analysis (DTA / TGA) according to DIN 51007:2019-04 (20℃-1500℃, heating rate 50K / min). The sample batches consisted of only three components: aluminum source, quartz powder, and soda ash. Specifically, the melting initiation temperature was determined. Figure 1 The DTA / TG curves for gibbsite and boehmite are shown in the figure. The melting onset temperature of gibbsite was measured to be 1071 °C, while that of boehmite was measured to be 1210 °C. This result indicates that gibbsite will begin to melt earlier than boehmite. This not only means less energy consumption in the melting process, but also that the aluminum source can have a positive impact on the melting and dissolution characteristics of SiO2 particles earlier in the molten state, even before they are reconfigured into cristobalite.

[0108] The melting process of different aluminum sources was further investigated by measuring the hemispherical temperature of different aluminum sources using hot-stage microscopy (HSM) at a heating rate of 5 K / min according to DIN 51730:2007-09 on cylindrical samples with a diameter of 3 mm and a height of 3 mm. The hemispherical temperature was defined as the temperature at which the sample has an approximately hemispherical shape and reaches half its original height with a shape factor ≥0.98. It is a characteristic value of the rheological properties at the start of the melting process. The sample batch consisted of a borosilicate glass mixture as illustrated above, differing only in the aluminum source. Two different types of gibbsite and one type of boehmite were compared. The two gibbsite types differ in BET surface area, average grain size, and density, with the first type corresponding to a variant of a particularly preferred aluminum raw material. The results are shown in the table below.

[0109]

[0110]

[0111] It is clear that the two gibbsite samples according to the present invention are superior to the boehmite sample. These values ​​indicate that the gibbsite sample begins to soften approximately 120°C-200°C earlier than the boehmite sample. Therefore, the glass composition will melt more easily with the gibbsite at a lower temperature.

[0112] Furthermore, the compositional changes during the melting process of the glass raw material mixture including an aluminum source according to the present invention were investigated. For this experiment, a 50g sample of the glass raw material mixture was prepared. The mixture was placed in a platinum crucible and heated to 1550°C. The sample was removed from the furnace every minute. The sample was quenched in water and then characterized by X-ray diffraction (XRD). The measurement results are as follows: Figure 2 As shown, after approximately 2 minutes, the composition is essentially quartz. After approximately 5 minutes, the quartz begins to transform into cristobalite, and after approximately 10 minutes, the entire quartz phase transforms into cristobalite. This indicates that particularly undesirable cristobalite particles are already present after a short period of approximately ten minutes. These cristobalite particles must then be melted and dissolved into the matrix over the next few hours of the melting process.

[0113] exist Figure 3 The image shows an example of GCI spheres in a tubular form of alumina-containing silicate glass. It can be seen that the tube-drawing process deforms the GCI spheres in the glass. The cristobalite crystal particles formed during the melting process are stretched into elongated ellipsoidal shapes with an aspect ratio of approximately 1.3:1 during the drawing process.

Claims

1. A method for manufacturing a glass article, said glass article having an alumina-containing silicate glass matrix, wherein, The method includes: - Provide raw material blanks, which include an alumina source and a SiO2 source; - Melt the raw material blank at a temperature exceeding 1500°C for no less than 3 hours; - Molded glass products; - Cool the glass article to room temperature; The alumina source is gibbsite, and the cooled glass matrix of the glass article contains less than one SiO2-rich glass sphere per 15g of glass with uneven composition.

2. The method according to claim 1, wherein, The forming of the glass product includes drawing glass tubes.

3. The method according to claim 1 or 2, wherein, The alumina source - Having an average particle size D50 of 20µm to 300µm; and / or - With a diameter of less than 5.0m 2 / g of BET surface area; and / or - With less than 2.600 g / cm³ 3 The density; and / or - Contains at least 0.015% by weight of sodium as determined by atomic absorption spectrometry.

4. The method according to claim 3, wherein, The alumina source has an average particle size D50 of 20µm to 150µm.

5. The method according to claim 1, wherein, The temperature of the melt does not exceed 1700℃.

6. The method according to claim 2, wherein, The forming of the glass product includes drawing glass tubes using the Danner tube drawing process.

7. Use of gibbsite as an alumina source in the manufacture of glass articles having an alumina-containing silicate glass matrix by any one of claims 1 to 6.

8. A glass article manufactured by the method according to any one of claims 1 to 6, comprising an alumina-containing silicate glass matrix, wherein each 15g of glass contains less than one compositionally inhomogeneous SiO2-rich glass sphere.

9. The glass article according to claim 8, the use according to claim 7, or the method according to any one of claims 1 to 6, wherein, The glass matrix includes - Amount of 3.0 mol% or more of B2O3, and / or - Less than 12.0 mol% of alkali metal oxides.

10. The glass article according to claim 8 or 9, the use according to claim 7, or the method according to any one of claims 1 to 6, wherein, The glass matrix has a strength of at least 0.75 W·m. -1 ·K -1 Thermal conductivity and / or coefficient of thermal expansion less than 5.0 ppm / K.

11. The glass article according to claim 8 or 9, the use according to claim 7, or the method according to any one of claims 1 to 6, wherein, The coefficient of thermal expansion of the glass matrix is ​​no more than 10.0 times greater than that of the GCI sphere.

12. The glass article according to claim 8 or 9, wherein it is in the form of a tube, sheet or disc.

13. The glass article according to claim 8 or 9, the use according to claim 7, or the method according to any one of claims 1 to 6, wherein the glass article has a UV transmittance of at least 60% at 200 nm with a thickness of 1 mm and / or a UV transmittance of at least 83% at wavelengths λ of 254 nm, 280 nm, and / or 310 nm, and / or at at least 10 cm at 254 nm and / or 200 nm. 2 The maximum UV transmittance deviation over the area is no more than 5.0%.

14. The glass article according to claim 8 or 9, wherein, The product - Having a thickness of at least 0.3 mm and / or at most 20 mm, and / or - Tempered by heat or by chemical tempering.

15. The glass article according to claim 8 or 9, having a fracture mode characterized in that it breaks into not less than 25 pieces in an area of ​​40 mm × 40 mm as measured according to DIN EN 12150-1.

16. The glass article according to claim 8 or 9, wherein, The thickness and UV transmittance of the glass product are selected such that, when using 120 W / cm, an arc length of 4 cm, and a UVC power density of 17.27 mW / cm², the desired UV transmittance is achieved. 2 When a medium-pressure mercury lamp is used to irradiate a portion of the glass product located 70 mm away from the product at an ambient temperature of 20°C for 5 seconds, the temperature of the surface of the glass product facing the portion of the product does not exceed 45°C.

17. The glass article according to claim 8, the use according to claim 7, or the method according to any one of claims 1 to 6, wherein, The glass matrix includes - Amount of 15.0 mol% or more of B2O3, and / or - Less than 10.0 mol% of alkali metal oxides.

18. The glass article according to claim 8 or 9, wherein, The article has a thickness of at least 3 mm and / or at most 20 mm.

19. The glass article according to claim 14, wherein, The article is heat-tempered or chemically tempered and has a compressive stress of at least 50 MPa on at least one surface.

20. A group of glass articles comprising 5 to 5,000 glass articles according to any one of claims 8 to 19.

Images