quartz glass body

Abstract

A method for manufacturing a quartz glass body, comprising forming a slurry from a powder of silicon dioxide particles and a liquid, treating the slurry with ultrasound to deagglomerate agglomerates formed in the slurry, and passing [it] through a multi-stage filter device to obtain a suspension of silicon dioxide; forming silicon dioxide particles from the suspension of silicon dioxide by granulation, forming a glass melt in a melting furnace and forming a quartz glass body from the glass melt; wherein the melting furnace has a gas outlet from which gas is withdrawn, wherein the dew point of the gas immediately after its withdrawal is below 0°C, wherein the multi-stage filter device has at least three filter stages, which each comprise at least one filter, wherein the first filter stage has a filter fineness of at least 5 pm, the second filter stage has a filter fineness of 0.5 pm to 5 pm and the third filter stage has a filter fineness of not more than 1 pm, wherein the separation rate of the first filter stage is at least 50%, the separation rate of the second filter stage is at least 95% and the separation rate of the third filter stage is at least 99.5%.

Description

[0001] This invention relates to a method for manufacturing quartz glass, the method comprising the following steps: i.) preparing silica powder and liquid; ii.) mixing the liquid with silica particles to obtain a slurry; iii.) ultrasonically treating the slurry to obtain a precursor suspension; iv.) passing the precursor suspension through a first multi-stage filtration device to obtain a silica suspension; v.) preparing silica particles from the silica suspension; vi.) preparing a glass melt from the silica particles in an oven; vii.) preparing a quartz glass from at least a portion of the glass melt, wherein treating the slurry in step iii.) includes deagglomerating at least a portion of the silica particles; wherein step v.) includes granulation, wherein the particle size of the silica particles is larger than the particle size of the silica particles contained in the silica suspension; wherein the oven has a crucible and a vent, through which gas is drawn from the slurry... The gas is removed from the oven; wherein the dew point of the gas leaving the oven via the vent is below 0°C; wherein the first multi-stage filtration device has at least a first filtration stage, a second filtration stage, and a third filtration stage, wherein the second filtration stage is arranged downstream of the first filtration stage and the third filtration stage is arranged downstream of the second filtration stage, wherein each filtration stage includes at least one filter, wherein the first filtration stage has a filtration fineness of 5 μm or greater, the second filtration stage has a filtration fineness in the range of 0.5 μm to 5 μm, and the third filtration stage has a filtration fineness of 1 μm or less, wherein the filtration fineness indicates the minimum particle size retained by the filter, wherein the separation rate associated with the first filtration stage is 50% or higher, the separation rate associated with the second filtration stage is 95% or higher, and the separation rate associated with the third filtration stage is 99.5% or higher, wherein the separation rate is specified according to ISO 16889 in each case. The invention also relates to quartz glass bodies obtainable by this method, as well as light guides, irradiators, arrangements, and molding bodies.

[0002] Quartz glass, quartz glass products, and products containing quartz glass are known. Various methods for manufacturing quartz glass and quartz glass bodies are known. Nevertheless, considerable effort is being made to determine methods for producing quartz glass of even higher purity (i.e., free of impurities).

[0003] In many applications of quartz glass and its processed products, high requirements are placed on uniformity and purity, especially for quartz glass processed into light guides or illuminators. Here, impurities can lead to absorption. This is detrimental because it causes the emitted light to be attenuated.

[0004] Ultraviolet lamps and their sleeves are used, for example, to disinfect water or air and surfaces. The aim is to emit ultraviolet radiation within a given wavelength range, where impurities reduce the efficiency of the radiation. For this reason, there is a certain preference for products utilizing synthetic quartz glass and / or products made from synthetic quartz glass. However, to be competitive in this market, quartz glass products must be inexpensive. Therefore, existing methods for manufacturing synthetic quartz glass products have no market.

[0005] Another example of the use of high-purity quartz glass is in semiconductor manufacturing processes. Here, any impurities in the glass can lead to defects in the semiconductor, resulting in scrap during production. Due to advancements in semiconductor manufacturing, such as narrower structure widths, higher packing densities, and stacking, coupled with an increasing number of process steps on the wafer and the use of larger wafers as substrates, the focus on impurities has significantly increased. Simultaneously, scrap costs have risen disproportionately. For these reasons, there is a need for reactors and production equipment that can transfer as little contaminant as possible to the wafer.

[0006] For these reasons, the industry has become quite interested in reactors and apparatus for synthetic quartz glass, where quartz glass from natural sources was previously used. The manufacture of high-purity quartz glass types used in these methods, especially high-purity synthetic quartz glass types, is very expensive. These quartz glasses are pricey. Nevertheless, the demand here is considerable.

[0007] However, synthetic quartz glass has disadvantages in some applications, particularly for reactors and apparatus in semiconductor manufacturing. For example, the lack of certain metal ions, especially aluminum, results in a lower viscosity for synthetic quartz glass compared to natural quartz glass. On the other hand, it has a relatively higher number of OH groups, which are generated, in particular, by flame hydrolysis during the production of silicon dioxide. This leads to a lower viscosity, and therefore a lower maximum operating temperature compared to natural quartz glass.

[0008] On the other hand, synthetic quartz glass lacking OH groups can be manufactured by treating the precursor stage (e.g., porous bodies or particles from nanoparticles) with chlorine, hydrochloric acid, etc., before the melting step. This removes the OH groups; however, the resulting quartz glass is now contaminated with chlorine and has lower viscosity, which eliminates some applications. Furthermore, the semiconductor industry is concerned that chlorinated quartz glass reactors may release chlorine, which can react with other metals to contaminate the wafer or corrode the structure built on it. Therefore, it is also desirable for synthetic quartz glass to not only lack OH groups but also be chlorine-free and possess high viscosity like natural quartz glass.

[0009] Given the market demand for the high-purity quartz glass mentioned above, especially high-purity synthetic quartz glass and products, it is highly attractive to manufacture high-quality synthetic quartz glass comparable to the aforementioned high-purity quartz glass, while being able to offer them at a lower price than quartz glass grades known to date on the market. With this in mind, cheaper production processes and cheaper sources of raw materials are being sought.

[0010] Known methods for manufacturing quartz glass include melting silica and molding the quartz glass from the melt. Irregularities within the glass (e.g., irregularities caused by encapsulated gas in the form of bubbles) can cause the glass to fail under stress, particularly at high temperatures, or may prevent it from being used for certain purposes. For example, if the raw materials used to manufacture quartz glass are contaminated, this can lead to the formation of cracks, bubbles, streaks, and discoloration within the quartz glass.

[0011] When used in processes for manufacturing and handling semiconductor components, contaminants in the quartz glass can leach out and transfer into the processed semiconductor parts. This is the case, for example, in etching processes, which then result in substandard semiconductor blanks. If gas inclusions are present, particles will form during the etching process used in semiconductor production if they leach out. This problem is also critically identified. Therefore, a common problem associated with known manufacturing methods is the substandard quality of the quartz glass used.

[0012] On the other hand, there's the issue of raw material efficiency. It seems advantageous to manufacture quartz glass products using industrial processing of quartz glass and raw materials that appear elsewhere as byproducts, rather than simply using these byproducts as fillers (e.g., in construction) or disposing of them as waste at a high price. These byproducts are typically trapped in filters as fine dust. This fine dust causes other problems, particularly in terms of health, workplace safety, and disposal.

[0013] Purpose of the invention

[0014] One object of the present invention is, in particular, to overcome one or more disadvantages arising from the prior art.

[0015] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings with long lifespans.

[0016] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings made of glass that are bubble-free or have a low bubble content.

[0017] Another object of the present invention is to provide light guides, irradiators, molded bodies and coatings made of glass with high transparency.

[0018] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings with low opacity.

[0019] Another object of the present invention is to provide a light guide with low attenuation.

[0020] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings with high profile accuracy. Specifically, the object of the present invention is to provide light guides, irradiators, molded bodies, and coatings that do not deform at high temperatures. More specifically, the object of the present invention is to provide light guides, irradiators, molded bodies, and coatings that are formably stable even when molded to have large dimensions.

[0021] Another object of the present invention is to provide tear-resistant and rupture-resistant light guides, irradiators, molded bodies, and coatings.

[0022] Another object of the present invention is to provide an efficient fabrication of light guides, irradiators, molded bodies, and coatings.

[0023] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings that are prepared cost-effectively.

[0024] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings that are prepared without requiring lengthy further processing steps, such as tempering.

[0025] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings with high thermal shock resistance. Specifically, the object of the present invention is to provide light guides, irradiators, molded bodies, and coatings that exhibit only small thermal expansion under large thermal fluctuations.

[0026] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings with high hardness.

[0027] Another object of the present invention is to provide photoconductors, irradiators, molded articles, and coatings with high purity and virtually no foreign atomic contamination. "Foreign atoms" refers to components that are not intentionally introduced.

[0028] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings containing low doping material content.

[0029] Another object of the present invention is to provide light guides, irradiators, molded articles, and coatings with high uniformity. The uniformity of a property or material is a measure of the uniformity of its distribution in a sample.

[0030] Specifically, the object of the present invention is to provide photoconductors, irradiators, molded bodies, and coatings with high material uniformity. Material uniformity is a measure of the uniformity of distribution of elements and compounds, particularly OH, chlorine, metals (especially aluminum, alkaline earth metals, and refractory metals), and dopants contained in a photoconductor, irradiator, or semiconductor device.

[0031] Another object of the present invention is to provide light guides, irradiators, molded bodies and coatings made of glass, the glass body of which does not attenuate the intensity of light in the visible range.

[0032] Another object of the present invention is to provide light guides, irradiators, molded bodies and coatings made of glass, the glass body of which attenuates radiation in the IR range as little as possible.

[0033] Another object of the present invention is to provide light guides, irradiators, molded bodies and coatings made of glass, the glass body of which is translucent to light in the IR range.

[0034] Another object of the present invention is to provide light guides, irradiators, molded bodies and coatings made of glass, wherein the glass body does not absorb light.

[0035] Another object of the present invention is to provide non-fluorescent light guides, irradiators, molded bodies, and coatings made of glass.

[0036] Specifically, the object of the present invention is to provide light guides, irradiators, molded bodies and coatings made of glass that do not fluoresce in the UV range, especially when excited by radiation with wavelengths of 254 nm or 365 nm or both.

[0037] Another object of the present invention is to provide light guides, irradiators, molded articles, and coatings made of glass with a defined OH content. A certain OH group content can help balance the structural changes in quartz glass caused by radiation such as UV, i.e., compensate for so-called radiation damage.

[0038] Another object of the present invention is to provide light guides, irradiators, molded bodies and coatings made of glass having a limited OH content in the range of 100ppm to 200ppm.

[0039] Another object of the present invention is to provide reactors, guides, molding bodies, and coatings that are particularly suitable for certain processing steps in semiconductor manufacturing, especially in wafer fabrication. Examples of such processing steps are plasma etching, chemical etching, and plasma.

[0040] Another object of the present invention is to provide reactors, guides, molded bodies and coatings that, when used in semiconductor production, particularly in the manufacture of wafers, help to minimize waste during semiconductor manufacturing.

[0041] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings having few or no metal ions.

[0042] The object of this invention is to provide photoconductors, irradiators, molded bodies, and coatings containing as few atoms as possible other than Si, O, and possibly H.

[0043] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings that can be used at high operating temperatures.

[0044] Another object of the present invention is to provide light guides, irradiators, molded bodies, and coatings that are stable even when used at high temperatures. Specifically, the object of the present invention is to provide light guides, irradiators, and components that do not emit particles during operation.

[0045] Another object of the present invention is to provide a quartz glass body suitable for use as a light guide, irradiator, molded body, and coating in quartz glass, and to at least partially solve at least one of the described objects, preferably multiple objects.

[0046] Another object of the present invention is to provide a quartz glass body with a linear design. Specifically, the object is to provide a quartz glass body with a high radius of curvature. More specifically, another object is to provide a quartz glass body with a high curl parameter.

[0047] Another objective is to provide a quartz glass in which cation migration is minimized.

[0048] Another objective is to provide a quartz glass that is as uniform as possible along its entire length.

[0049] Specifically, the object of the present invention is to provide a quartz glass having a high refractive index over the entire length of the quartz glass.

[0050] Specifically, the object of the present invention is to provide a quartz glass body with highly uniform viscosity along the entire length of the quartz glass body.

[0051] Specifically, the object of the present invention is to provide a quartz glass body with high material homogeneity along the entire length of the quartz glass body.

[0052] Specifically, the object of the present invention is to provide a quartz glass body with high optical uniformity over the entire length of the quartz glass body.

[0053] Another object of the present invention is to provide a quartz glass having a limited OH content.

[0054] Another object of the present invention is to provide a quartz glass with a low OH content.

[0055] Another object of the present invention is to provide a quartz glass with high viscosity.

[0056] Another object of the present invention is to provide a quartz glass that can be used at the highest possible temperature.

[0057] Another object of the present invention is to provide a quartz glass lacking OH.

[0058] Another object of the present invention is to provide a quartz glass containing little or no chlorine. Another object of the present invention is to provide a quartz glass that is not significantly contaminated by crucible material.

[0059] Specifically, the purpose of this invention is to provide a quartz glass with low metal contaminant content.

[0060] Specifically, the object of the present invention is to provide a quartz glass with a low tungsten content.

[0061] Specifically, another object of the present invention is to provide a quartz glass with a low molybdenum content.

[0062] Another object of the present invention is to manufacture a quartz glass body with little or no contamination from the crucible material, particularly tungsten and molybdenum.

[0063] Another object of the present invention is to provide a quartz glass body that is lacking in OH, chlorine and metal contaminants, while having high viscosity, high temperature stability and being usable at high temperatures.

[0064] Another object of the present invention is to provide a quartz glass body having the lowest possible OH, chlorine and metal contaminants, while also having high viscosity, high temperature stability and being usable at high temperatures, and also being manufactured more cheaply than other synthetic quartz glasses.

[0065] Another object of the present invention is to provide a quartz glass having very few OH groups, as little or no chlorine as possible, and no or as low a metallic component as possible. Simultaneously, the quartz glass should have high viscosity, high temperature stability, and be usable at high temperatures, and should be able to be manufactured at the same cost, less cost, or at least cheaper (if possible) than natural quartz glass.

[0066] Another object of the present invention is to provide a quartz glass body and its subsequent products, such as light guides, irradiators, molded bodies, coatings, reactors, and directors, wherein the quartz glass body and its subsequent products (as applicable) do not fluoresce when irradiated with light in the UV range, particularly at wavelengths of 254 nm or 365 nm, and also have very few OH groups and contain as little chlorine as possible or no chlorine. Furthermore, such quartz glass bodies and subsequent products should also be usable at high temperatures and have high viscosity. More specifically, it is also an object of the present invention to provide a quartz glass body having a combination of more than one of the aforementioned features.

[0067] Another object of the present invention is to provide a method for manufacturing quartz glass that at least partially solves some of the objects already described above.

[0068] Another object of the present invention is to provide a method for preparing quartz glass more simply.

[0069] Another object of the present invention is to provide a method for continuously preparing quartz glass.

[0070] Another object of the present invention is to provide a method for preparing quartz glass through a continuous melting and forming process.

[0071] Another object of the present invention is to provide a method for rapidly forming quartz glass.

[0072] Another object of the present invention is to provide a method for preparing quartz glass with a low scrap rate.

[0073] Another object of the present invention is to provide a method for preparing a trimmable quartz glass body.

[0074] Another object of the present invention is to provide an automated method for preparing quartz glass.

[0075] Another object of the present invention is to provide a method for preparing quartz glass, wherein silica particles can be processed in a melting oven, for example by temperature treatment greater than 1000°C, without subjecting them to an intentional compaction step beforehand.

[0076] Specifically, the object of the present invention is to provide a method for preparing quartz glass, wherein a BET of 20m can be used. 2 / g or higher silica particles are introduced into a melting oven, melted and processed to obtain quartz glass.

[0077] Another object of the present invention is to provide a method for preparing quartz glass, wherein the components have the longest possible expected lifespan under process conditions.

[0078] Specifically, the object of the present invention is to provide a method for preparing quartz glass, wherein furnace corrosion is avoided.

[0079] Another object of the present invention is to provide a method for preparing quartz glass, wherein a silica source material with high residual moisture can be used. "Silica source material" means, for example, silica particles.

[0080] Specifically, the object of the present invention is to provide a method for preparing quartz glass, wherein a silica input material with high residual moisture can be used without a pretreatment step.

[0081] Specifically, another object of the present invention is to provide a method for preparing quartz glass, wherein a silica input material with high residual moisture can be used in a system containing a melting crucible with refractory metals.

[0082] Another object of the present invention is to provide a method for preparing a glass body, wherein the component has the longest possible service life under process conditions.

[0083] Another object of the present invention is to provide a method for preparing a vitreous body having a defined OH content.

[0084] Another object of the present invention is to provide a method for preparing a quartz glass with a low OH content.

[0085] Another object of the present invention is to provide a method for preparing quartz glass with a defined ODC (oxygen-deficient center) content.

[0086] Another object of the present invention is to provide a method for preparing quartz glass with a high ODC (oxygen-deficient center) content.

[0087] Another object of the present invention is to provide a method for preparing quartz glass in which the input of impurities from the furnace is low.

[0088] Another object of the present invention is to provide a method for preparing quartz glass, wherein hygroscopic silica particles can be processed without shortening the working life of the crucible, especially when the crucible is substantially uncorroded.

[0089] Another object of the present invention is to provide a method for preparing quartz glass with low gas consumption. Specifically, the object of the present invention is to provide a method for manufacturing quartz glass with low helium consumption. Specifically, the object of the present invention is to provide a method for preparing quartz glass with low hydrogen consumption.

[0090] Another object of the present invention is to provide a method for preparing a quartz glass, wherein the quartz glass and any subsequent products made therefrom do not fluoresce when irradiated with UV light, particularly at wavelengths of 254 nm or 365 nm, and also have very few OH groups and contain as little chlorine as possible or none at all. Furthermore, such quartz glass and subsequent products should be usable even at high temperatures and have high viscosity.

[0091] Another object of the present invention is to present a method for preparing high-purity quartz glass.

[0092] Another object of the present invention is to present a method for preparing quartz glass containing as few bubbles as possible.

[0093] Another object of the present invention is to present a method for preparing quartz glass free of metal contaminant particles.

[0094] Another objective is to continue improving the processability of quartz glass.

[0095] Another task is to continue improving the workability of quartz glass. Summary of the Invention

[0096] This invention is particularly based on the understanding that only a combination of several measures can be used to manufacture quartz glass with significantly improved quality and specific characteristics. Using this method, silica powder, and even soot powder—that is, byproducts or waste products obtainable from another glass synthesis—can be used to prepare high-quality quartz glass comparable to other high-quality synthetic quartz glass products. This is especially unaffected by contamination from gaseous inclusions or foreign atoms (i.e., atoms other than silicon and oxygen). The combination of measures includes adding silicon components other than silica, such as silicon, filtering the resulting silica suspension as an intermediate step, and monitoring the dew point of the gas stream flowing from the crucible.

[0097] By changing a single parameter, the main characteristics of the quartz glass that can be prepared can be managed using the amount of silicon components other than silica. These characteristics include its viscosity, the presence and extent of electromagnetic radiation absorption in the UV range, the presence and extent of electromagnetic radiation absorption in the IR range, or a combination of several of these characteristics.

[0098] Whenever a process step involving melting particles to obtain a glass melt is involved, the addition of silicon can be used to control the amount of OH groups and / or hydrogen molecules in the crucible, thereby preventing crucible corrosion and potential contamination of the glass melt. The conditions in the crucible can be effectively controlled by determining the dew point of the gas flowing from the crucible. Here, again, no foreign atoms (i.e., those atoms other than silicon and oxygen) are introduced into the resulting quartz glass.

[0099] The aforementioned silica powder can be used to manufacture high-quality quartz glass. If the soot powder is first processed into granules via a slurry and the slurry is filtered before granulation, its quality can be compared to other synthetic quartz glass products of comparable quality. This method makes a significant contribution to avoiding the formation of bubbles due to contaminants that can oxidize into gases and gaseous inclusions.

[0100] Embodiments of the present invention

[0101] The subject matter of the independent claim contributes to achieving at least one of the aforementioned objectives. The dependent claims are preferred embodiments that help to at least partially satisfy at least one of the stated objectives.

[0102] |1| A method for manufacturing quartz glass, the method comprising the following process steps:

[0103] i.) Provide silica particles as powder and provide liquid;

[0104] ii.) The powder and liquid are mixed to obtain a slurry containing the liquid and the silica particles;

[0105] iii.) The slurry is treated with ultrasound to obtain a precursor suspension;

[0106] iv.) Pass at least a portion, preferably all of the entire precursor suspension, through at least a first multi-stage filtration device to obtain a silica suspension;

[0107] v.) Preferably, silica particles are formed from the silica suspension by spray drying;

[0108] vi.) Forming a glass melt from the silica particles in an oven;

[0109] vii.) A quartz glass body is formed from at least a portion of the glass melt;

[0110] Step iii.) of the process of the slurry includes depolymerizing at least a portion of the silica particles;

[0111] Step v.) includes granulation;

[0112] The particle size of the silica particles is larger than the particle size of the silica particles contained in the silica suspension.

[0113] The oven described above has a crucible and a gas outlet.

[0114] The gas is drawn out from the oven via the gas outlet;

[0115] The gas has a dew point below 0°C when it exits the oven via the gas outlet.

[0116] The first multi-stage filtration device has at least a first filtration stage, a second filtration stage, and a third filtration stage.

[0117] The second filter stage is arranged downstream of the first filter stage, and the third filter stage is arranged downstream of the second filter stage.

[0118] Each filtration stage contains at least one filter.

[0119] The first filtration stage has a filtration fineness of 5 μm or greater, the second filtration stage has a filtration fineness in the range of 0.5 μm to 5 μm, and the third filtration stage has a filtration fineness of 1 μm or less.

[0120] The filtration fineness refers to the minimum particle size retained by the filter.

[0121] The separation rate of the first filtration stage is 50% or higher, the separation rate of the second filtration stage is 95% or higher, and the separation rate of the third filtration stage is 99.5% or higher, wherein the separation rate is specified in accordance with ISO 16889 in each case.

[0122] |2|The granulation method according to embodiment 1 is selected from the group consisting of: roller granulation, spray granulation, centrifugal atomization, cryogenic granulation and fluidized bed granulation.

[0123] |3|According to one of the methods described in the above embodiments, a silicon component other than silicon dioxide is added in at least one of the process steps.

[0124] |4|The method according to one of the above embodiments, wherein the silicon component other than silicon dioxide is silicon, silicon-hydrogen compound, silicon-oxygen compound or silicon-hydrogen-oxygen compound, with silicon being particularly preferred.

[0125] |5|The method according to one of the above embodiments, wherein the silicon component is added in powder form.

[0126] |6|The method according to one of the above embodiments, wherein the silicon component is added in liquid or gas form.

[0127] |7|According to one of the methods described in the above embodiments, the silicon component other than silicon dioxide is added in one of steps i.), ii.) or v.), or during more than one of the steps, particularly preferably during step v.).

[0128] |8|The method according to one of the embodiments|3| to|7|, wherein the total amount added to one or more silicon components other than silicon dioxide is from 10 ppm to 100,000 ppm, ppm relative to the total weight of silicon dioxide.

[0129] |9|According to one of the above embodiments, the method wherein forming the particles in step v.) comprises spray drying the silica suspension formed in step iv.), wherein the spray drying is performed by spraying the silica suspension via nozzles in a spray tower, wherein the spray drying is characterized by at least one of the following features:

[0130] a) Spray granulation in a spray tower;

[0131] b] The silica suspension is pressurized at the nozzle to no more than 40 bar, for example in the range of 1.3 bar to 20 bar or 1.5 bar to 18 bar, or 2 bar to 15 bar or 4 bar to 13 bar, or particularly preferably in the range of 5 bar to 12 bar, wherein the pressure is an absolute pressure (relative to p = 0 hPa).

[0132] c] The temperature of the droplets when they enter the spray tower is in the range of 10°C to 50°C, preferably in the range of 15°C to 30°C, and particularly preferably in the range of 18°C ​​to 25°C.

[0133] d] The temperature of the side of the nozzle facing the spray tower is in the range of 100°C to 450°C, for example, in the range of 250°C to 440°C, and particularly preferably in the range of 350°C to 430°C;

[0134] e] The flow rate of the silica suspension through the nozzle is 0.05m. 3 / h to 1m 3 Within the range of / h, for example, in 0.1m 3 / h to 0.7m 3 / h or 0.2m 3 / h to 0.5m 3 Within the range of / h, it is particularly preferred to be within 0.25m. 3 / h to 0.4m 3 Within the range of / h;

[0135] f] In each case, based on the total weight of the silica suspension, the silica suspension has a solid content of at least 40% by weight, for example in the range of 50% to 80% by weight or in the range of 55% to 75% by weight, particularly preferably in the range of 60% to 70% by weight;

[0136] g] The gas flow entering the spray tower is in the range of 10 kg / min to 100 kg / min, for example, in the range of 20 kg / min to 80 kg / min or 30 kg / min to 70 kg / min, and particularly preferably in the range of 40 kg / min to 60 kg / min;

[0137] h] The temperature of the gas stream entering the spray tower is in the range of 100°C to 450°C, for example, in the range of 250°C to 440°C, and particularly preferably in the range of 350°C to 430°C;

[0138] i] The temperature of the gas stream exiting the spray tower is below 170°C;

[0139] j] The gas is selected from the group consisting of: air, nitrogen, and helium, or a combination of two or more thereof; preferably air;

[0140] [k] In each case, based on the total weight of the silica particles obtained by spray drying, the particles taken out of the spray tower have a residual moisture content of less than 5%, for example less than 3% by weight or less than 1% by weight or in the range of 0.01% by weight to 0.5% by weight, particularly preferably in the range of 0.1% by weight to 0.3% by weight;

[0141] Based on the total weight of the silica particles obtained by the spray drying, at least 50% by weight of the sprayed particles are completed within a flight time of 1 to 100 seconds, for example, within a period of 10 to 80 seconds, and particularly preferably within a period of 25 to 70 seconds.

[0142] Based on the total weight of silica particles obtained by the spray drying, at least 50% by weight of the spray particles fly for more than 20 m, for example, more than 30 m, or more than 50 m, or more than 70 m, or more than 100 m, or more than 150 m, or more than 200 m, or in the range of 20 m to 200 m, or 10 m to 150 m, or 20 m to 100 m, particularly preferably in the range of 30 m to 80 m;

[0143] The spray tower described in n] has a cylindrical geometry;

[0144] o] The height of the spray tower is greater than 10m, for example greater than 15m, or greater than 20m, or greater than 25m, or greater than 30m, or in the range of 10m to 25m, particularly preferably in the range of 15m to 20m;

[0145] p] Before removing the particles from the spray tower, particles smaller than 90 μm are screened;

[0146] q] After the particles are removed from the spray tower, it is preferable to filter out particles with a size greater than 500 μm on a vibrating table;

[0147] The silica suspension droplets are discharged from the nozzle at an angle of 30° to 60° with respect to the vertical direction, particularly preferably at an angle of 45° with respect to the vertical direction.

[0148] |10|The method according to one of the above embodiments, wherein molten energy impacts the fixed surface of the silica particles.

[0149] |11| According to one of the above embodiments, the gas has a dew point at least 30°C lower than its dew point when it exits the oven via the gas outlet.

[0150] |12| According to one of the methods described above, the melting furnace is at least partially made of a material containing one or more metals selected from molybdenum, tungsten, rhenium, iridium and osmium.

[0151] |13| According to one of the methods described in the above embodiments, the quartz glass contains one or more metals selected from molybdenum, tungsten, rhenium, iridium and osmium in total less than 1000 ppb, the total amount being based on the total weight of the quartz glass.

[0152] |14| According to one of the methods described in the above embodiments, the dew point is determined in a test unit, wherein the test unit is separated from the gas stream discharged from the gas outlet by a membrane.

[0153] |15|The method according to one of the above embodiments, wherein a dew point level hygrometer is used to determine the humidity level.

[0154] |16|The method according to one of the above embodiments, wherein the oven gas space contains hydrogen, helium, nitrogen, or a combination of two or more thereof.

[0155] |17| According to one of the methods described above, the silica powder may be made of a compound selected from the group consisting of siloxanes, silanolates and silicon halides.

[0156] |18|The method according to one of the above embodiments, wherein the first filtering device is characterized by at least one of the following features:

[0157] (a) The first filtration stage has a filtration fineness of 5 μm or greater, for example, 5 μm to 15 μm;

[0158] (b) The first filtration stage has a separation rate of 90% or lower, for example, in the range of 50% to 90%;

[0159] (c) The second filtration stage has a filtration fineness of 0.5 μm or greater, for example, in the range of 0.5 μm to 10 μm;

[0160] (d) The second filtration stage has a separation rate of 80% or higher, for example, 99.5% or higher;

[0161] (e) The third filtration stage has a filtration fineness of 0.5 μm or greater, for example, in the range of 0.5 μm to 10 μm or 0.1 μm to 1 μm;

[0162] (f) The third filtration stage has a separation rate of 80% or higher, for example, 99.5% or higher.

[0163] Or a combination of at least two of features (a) to (f).

[0164] |19| According to one of the methods described in the above embodiments, the first filtration device is designed as a depth filter in at least one filter selected from the first filtration stage, the second filtration stage, and the third filtration stage.

[0165] |20|The method according to one of the above embodiments, wherein the slurry is treated with ultrasound for at least 10 seconds.

[0166] |21|The method according to one of the above embodiments, wherein the slurry is treated with ultrasound at a power density of up to 600 W / l.

[0167] |22| According to one of the methods described above, the slurry has less than 5% by weight of additives to stabilize the slurry, the wt. weight being based on the total weight of the slurry.

[0168] |23|The method according to one of the above embodiments, wherein the silica powder

[0169] It has at least one of the following characteristics:

[0170] a. At most 35m 2 / g, for example 25m 2 / g to 35m 2 / g, or 20m 2 / g to 35m 2 / g, or 25m 2 / g to 30m 2 BET surface area within the range of / g; and

[0171] b. at 0.01 g / cm 3 Up to 0.3 g / cm 3 Bulk density within the range;

[0172] c. Carbon content less than 100 ppm;

[0173] d. Chlorine content less than 500 ppm;

[0174] e. Aluminum content less than 200 ppb;

[0175] f. The content of atoms other than Si, O, H, C, and Cl less than 5 ppm;

[0176] g. At least 70% by weight of the powder particles have a primary particle size in the range of 10 nm to 100 nm;

[0177] h. at 0.001 g / cm 3 Up to 0.3 g / cm 3 Filling density within the range;

[0178] i. Residual moisture content less than 5% by weight;

[0179] j. Particle size distribution D in the range of 1 μm to 7 μm 10 ;

[0180] k. Particle size distribution in the range of 6 μm to 15 μm D 50 ;

[0181] l. Particle size distribution in the range of 10 μm to 40 μm D 90 ;

[0182] Or a combination of two or more of the features a to l;

[0183] The weight percentage in each case is based on the total amount of the silica powder.

[0184] The particle size distribution D of the silica powder 10 D 50 and D 90 Measured on a Mastersizer 2000, by laser refraction according to method x.

[0185] |24| According to the method of one of the above embodiments, the slurry has at least one of the following characteristics:

[0186] A.) Based on the dry weight of the slurry, a solid content of at least 20% by weight;

[0187] B.) As 4% by weight of the slurry, the slurry has a pH value in the range of 3 to 8;

[0188] C.) At least 90% by weight of the silica particles have a particle size in the range of 1 nm to <100 μm;

[0189] D.) Chlorine atom content of 500 ppm or lower; and

[0190] E.) 5% of the content of atoms other than Si, O, H, C, and Cl.

[0191] F.) The slurry is vibrated and coagulated;

[0192] Where wt.-% weight and ppm are always based on the total solids content of the slurry;

[0193] G.) The slurry is conveyed in contact with the plastic surface;

[0194] The slurry described in H.) is sheared;

[0195] I.) The slurry has a temperature exceeding 0°C, preferably in the range of 5°C to 35°C;

[0196] J.) According to DIN 53019-1 (5 rpm, 30% by weight), the slurry has a viscosity in the range of 500 mPas to 2000 mPas, for example in the range of 600 mPas to 1700 mPas, and particularly preferably in the range of 650 mPas to 1350 mPas.

[0197] K.) In 4% by weight of the slurry, at least 5% of the silica particles have a particle size in the range of >10 μm, according to DIN ISO 13320-1.

[0198] |25| According to the method of one of the above embodiments, the silica suspension has at least one of the following characteristics:

[0199] A. Coagulation characteristics at temperatures below 45°C and at solid concentrations ranging from 20% to 70% by weight, the weight percentage being based on total solids in the suspension;

[0200] B. According to DIN ISO 13320-1, at least 90% by weight of the silica particles, based on the total weight of all silica particles, have a particle size in the range of 1 nm to <10 μm, wherein the percentage by weight is based on the solids content of the silica suspension;

[0201] C. A pH value in the range of 3 to 8, wherein the pH value is based on a silica suspension with a solid content of 4% by weight;

[0202] D. Chlorine content less than 500 ppm;

[0203] E. Aluminum content less than 200 ppb;

[0204] F. The content of atoms other than Si, O, H, C, and Cl less than 5 ppm;

[0205] G. Temperatures exceeding 0°C, preferably within the range of 5°C to 35°C;

[0206] H. Viscosity in the range of 500 mPas to 2000 mPas, for example, in the range of 600 mPas to 1700 mPas, particularly preferably in the range of 650 mPas to 1350 mPas, according to DIN 53019-1 (5 rpm, 30 wt%).

[0207] The ppm and ppb values ​​in each case are based on the total amount of silica particles in the suspension.

[0208] 26 | According to one of the methods described in the above embodiments, the first multi-stage filter has a service life of at least 250 liters, the liters being based on the filtration volume of the precursor suspension filtration device.

[0209] |27|The method according to one of the above embodiments, wherein at least one additional filtration device is used downstream of the first multi-stage filtration device.

[0210] |28| According to one of the methods described in the above embodiments, the silica particles formed in step v.) have at least one of the following characteristics:

[0211] [A] at 20m 2 / g to 50m 2 BET surface area within the range of / g;

[0212] [B] Average particle size in the range of 180 μm to 300 μm;

[0213] [C] at 0.5 g / cm 3 Up to 1.2 g / cm 3 Bulk density within the range;

[0214] [D] Carbon content less than 50 ppm;

[0215] [E] Aluminum content less than 200 ppb;

[0216] [F] at 0.5 g / cm 3 Up to 1.3 g / cm 3 Filling density within the range;

[0217] [G] Pore volume in the range of 0.1 ml / g to 1.5 ml / g;

[0218] [H] Chlorine content less than 200 ppm,

[0219] [I] The content of metals other than aluminum less than 1000 ppb;

[0220] [J] Residual moisture content less than 10% by weight;

[0221] [K] Particle size distribution in the range of 50 μm to 150 μm D 10 ;

[0222] [L] Particle size distribution in the range of 150 μm to 300 μm D 50 ;

[0223] [M] Particle size distribution in the range of 250 μm to 620 μm D 90 ;

[0224] [N] Angle of accumulation in the range of 23° to 29°;

[0225] The weight percentages (%), ppm, and ppb are, in each case, based on the total weight of the silica particles.

[0226] |29|According to one of the above embodiments, the silica particles obtained in step v.) are heat-treated prior to step vi.), wherein the obtained treated silica particles have at least one of the following characteristics:

[0227] (A) at 10m 2 / g to 35m 2 BET surface area within the range of / g;

[0228] (B) Average particle size in the range of 100 μm to 300 μm;

[0229] (C) at 0.7 g / cm 3 Up to 1.2 g / cm 3 Bulk density within the range;

[0230] (D) Carbon content less than 5 ppm;

[0231] (E) Aluminum content less than 200 ppb;

[0232] (F) at 0.7 g / cm 3 Up to 1.2 g / cm 3 Filling density within the range;

[0233] (G) Pore volume in the range of 0.1 ml / g to 2.5 ml / g;

[0234] (H) Chlorine content less than 500 ppm,

[0235] (I) The content of metals other than aluminum less than 1000 ppb;

[0236] (J) Residual moisture content less than 3% by weight,

[0237] (K) Particle size distribution in the range of 50 μm to 150 μm D 10 ;

[0238] (L) Particle size distribution in the range of 150 μm to 250 μm D 50 ;

[0239] (M) Particle size distribution in the range of 250 μm to 450 μm D 90 ;

[0240] (N) Angle of accumulation in the range of 23° to 29°;

[0241] The weight percentages (%), ppm, and ppb are, in each case, based on the total weight of the silica particles.

[0242] |30| A quartz glass body, said quartz glass body having the following characteristics:

[0243] A] Chlorine content less than 60 ppm;

[0244] B] Aluminum content less than 200 ppb;

[0245] C] The content of atoms other than Si, O, H and C is less than 5 ppm;

[0246] D] in log 10 (η(1250℃) / dPas)=11.4 to log 10 (η(1250℃) / dPas)=12.9, or log 10 (η(1300℃) / dPas)=11.1 to log 10 (η(1300℃) / dPas)=12.2, or log 10 (η(1350℃) / dPas)=10.5 to log 10 Viscosity in the range of (η(1350℃) / dPas)=11.5 (p=1013hPa);

[0247] E] Less than 10 -4 The uniformity of refractive index;

[0248] F] Cylindrical shape;

[0249] G] Tungsten content less than 100 ppb;

[0250] Molybdenum content (H) less than 100 ppb;

[0251] The ppb and ppm are each based on the total weight of the quartz glass.

[0252] |31| A quartz glass body that can be obtained by means of a method according to any one of embodiments |1| to |29|.

[0253] |32|The quartz glass body according to embodiment |31| is characterized by at least one feature of embodiment |30|.

[0254] |33| A method for manufacturing an optical guide, the method comprising the following steps:

[0255] A / Provide a quartz glass body according to any one of embodiments |30| to |32|, or obtain a quartz glass body using the method according to claim 1, wherein the quartz glass body is first processed to obtain a hollow body having at least one opening;

[0256] B / Insert one or more mandrels into the hollow body from step A / through the at least one opening to obtain a precursor;

[0257] C / The precursor is stretched when heated to obtain an optical guide having one or more cores and a jacket M1.

[0258] |34| An optical guide, said optical guide can be obtained by the method according to embodiment |33|.

[0259] |35| A method for manufacturing an irradiation body, the method comprising the following steps:

[0260] (i) Providing a quartz glass body according to any one of embodiments |30| to |32|, or obtaining a quartz glass body by the method according to claim 1, wherein the quartz glass body is first processed into a hollow body having at least one opening;

[0261] (ii) If necessary, assemble the hollow body with the electrodes;

[0262] (iii) Fill the hollow body from step (i) with gas.

[0263] |36| An irradiation body, which can be obtained by the method according to embodiment |35|.

[0264] |37| A method for manufacturing a molded article, the method comprising the following steps:

[0265] (1) Providing a quartz glass body according to any one of embodiments |30| to |32|, or obtaining a quartz glass body by the method according to claim 1, and

[0266] (2) The quartz glass body is shaped to obtain a molded body.

[0267] |38| A molded body, said molded body can be obtained by the method according to embodiment |37|.

[0268] General Precautions

[0269] In this specification, the scope of a statement also includes values ​​stated as limits: therefore, a statement of the class "within the range of x to y" regarding the variable a means that a can take the values ​​x, y, and values ​​between x and y. A range of one side of the class "at most y" regarding the variable means the value y is less than y. Detailed Implementation

[0270] The independent claims help to at least partially satisfy at least one of the above objectives. The dependent claims present preferred embodiments that help to at least partially satisfy at least one of the stated objectives.

[0271] The first objective of this invention is a method for manufacturing quartz glass, the method comprising the following process steps:

[0272] i.) Preparation of powders and liquids containing silica particles;

[0273] ii.) Forming a slurry containing the liquid and the silica particles;

[0274] iii.) The slurry is treated with ultrasound to obtain a precursor suspension;

[0275] iv.) Pass at least a portion / preferably the entire precursor suspension through at least a first multi-stage filtration device to obtain a silica suspension;

[0276] v.) Forming silica particles from the silica suspension by, for example, spray granulation or roller granulation;

[0277] vi.) Forming a glass melt from the silica particles in an oven;

[0278] vii.) A quartz glass body is formed from at least a portion of the glass melt;

[0279] The treatment of the slurry in step iii.) includes depolymerizing at least a portion of the silica particles;

[0280] Step v.) includes granulation;

[0281] The particle size of the silica particles is larger than the particle size of the silica particles contained in the silica suspension.

[0282] The oven described above has a crucible and a gas outlet.

[0283] The gas is taken out from the oven via the gas outlet;

[0284] The gas has a dew point below 0°C when it leaves the oven via the gas outlet.

[0285] The first multi-stage filtration device has at least a first filtration stage, a second filtration stage, and a third filtration stage, wherein the second filtration stage is arranged downstream of the first filtration stage, and the third filtration stage is arranged downstream of the second filtration stage.

[0286] Each filtration stage includes at least one filter.

[0287] The first filtration stage has a filtration fineness of 5 μm or greater, the second filtration stage has a filtration fineness in the range of 0.5 μm to 5 μm, and the third filtration stage has a filtration fineness of 1 μm or less.

[0288] The filtration fineness refers to the minimum particle size retained by the filter.

[0289] The separation rate of the first filtration stage is 50% or higher, the separation rate of the second filtration stage is 95% or higher, and the separation rate of the third filtration stage is 99.5% or higher, wherein the separation rates are calculated according to ISO 16889 in each case.

[0290] Silica particles powder

[0291] In step i.), the powder is made from silica particles. Silica particle powder is also referred to as silica particle powder. Using this invention, silica powder can be obtained in principle from naturally occurring or synthetic silica, preferably synthetic silica powder. Silica powder prepared by pyrolysis is particularly preferred.

[0292] The silica powder can be any silica powder having at least two particles. The preparation method can be any method that a person skilled in the art would consider generally available and suitable for the purposes of this invention.

[0293] According to one embodiment of the invention, silica powder is generated as a byproduct during the manufacture of quartz glass, particularly during the manufacture of so-called "fly ash bodies". Silica generated in this manner is also commonly referred to as "fly ash dust".

[0294] A suitable source of silica powder is silica particles obtained during the manufacture of synthetic soot using a flame hydrolysis burner. During soot manufacture, a rotating carrier tube with a cylindrical jacket surface moves back and forth along a row of burners. Oxygen and hydrogen can be added to the flame hydrolysis burner, along with the initial material for manufacturing primary silica particles. The primary silica particles preferably have a primary particle size of up to 100 nm. The primary silica particles obtained by flame hydrolysis aggregate or agglomerate to form silica particles with a particle size of about 9 μm (DIN ISO 13320:2009-1). Primary silica particles can be identified and their primary particle size can be determined using scanning electron microscopy. Some silica particles are separated onto the cylindrical jacket surface of the carrier tube rotating about its longitudinal axis, building up the soot layer by layer. Other silica particles are not separated onto the cylindrical jacket surface of the carrier tube but appear as dust, for example, in a filtration system. This other portion of silica particles forms silica powder, commonly referred to as "fly ash." Typically, based on the total weight of the silica particles, the amount of silica particles separated onto the carrier tube is greater than the amount of silica particles present in the portion during the manufacture of the fly ash.

[0295] Currently, soot is disposed of as waste in a cumbersome and costly manner, or used without added value as a filler in road construction, as an additive in the dye industry, as a raw material for tile manufacturing, and as hexafluorosilicic acid for cleaning building foundations. In this invention, soot is a suitable starting material and can be processed into high-value products.

[0296] Silica prepared by flame hydrolysis is generally called pyrolytic silica. Pyrolytic silica can usually be obtained in the form of amorphous primary silica particles or silica particles.

[0297] According to one embodiment, silica powder can be prepared from a gas mixture by flame hydrolysis. In this case, silica particles are also formed during flame hydrolysis and separated as silica powder before any agglomerates or aggregates form. The main product here is silica powder, referred to above as soot dust.

[0298] The source material used for preparing silica powder is preferably an organic or inorganic silicon compound. Non-halogenated silicon compounds are also preferred. Among organosilicon compounds, compounds in which silicon atoms are directly bonded to oxygen atoms are particularly preferred, especially siloxanes and silanolates. "Siloxane" refers to linear and cyclic polyalkylsiloxanes. Polyalkylsiloxanes preferably have the general formula:

[0299] Si p O p R 2p ,

[0300] Where p is at least 2, preferably 2 to 10, particularly preferably an integer of 3 to 5, and R is an alkyl group having one to eight C atoms, preferably having one to four C atoms, particularly preferably a methyl group.

[0301] Particularly preferred are siloxanes selected from the group consisting of hexamethyldisiloxane, hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5), or combinations of two or more thereof. If the siloxane comprises D3, D4, and D5, then D4 is preferably the major component. The major component preferably comprises at least 70% by weight, preferably at least 80% by weight, for example at least 90% by weight or at least 94% by weight, particularly preferably at least 98% by weight, in each case based on the total amount of silica powder. Preferred siloxanes are tetramethoxysilane and methyltrimethoxysilane.

[0302] Suitable inorganic silicon compounds for use as silica powder input materials include silicon halides, silicates, silicon carbide, and silicon nitride. Particularly preferred inorganic silicon compounds for use as silica powder input materials are silicon tetrachloride and trichlorosilane.

[0303] According to one embodiment, the silica powder can be made from a group selected from siloxanes and silanolates.

[0304] Silica powder is preferably made from compounds selected from the group consisting of: hexamethyldisiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, tetramethoxysilane and methyltrimethoxysilane or combinations of two or more thereof, with particular preference being made from octamethylcyclotetrasiloxane.

[0305] When preparing silica from silicon tetrachloride by flame hydrolysis, various parameters are important. A suitable gas mixture preferably contains an oxygen proportion ranging from 25 vol% to 40 vol% during flame hydrolysis. The hydrogen proportion can range from 45 vol% to 60 vol%. The silicon tetrachloride proportion is preferably from 5 vol% to 30 vol%, all of which are based on the total volume of the gas stream. A combination of the volume components of oxygen, hydrogen, and SiCl4 is also preferred. The flame in the flame hydrolysis is preferably in the range of 1500°C to 2500°C, for example, in the range of 1600°C to 2400°C, and particularly preferably in the range of 1700°C to 2300°C. The primary silica particles formed during flame hydrolysis are preferably separated as silica powder before any agglomerates or aggregates form.

[0306] Silica powder may have at least one, for example at least two, at least three, or at least four, preferably at least five of the following characteristics:

[0307] a. In less than 35m 2 Within the range of / g, for example, 25m 2 / g to 35m 2 / g, or 20m 2 / g to 35m 2 / g, or 25m 2 / g to 30m 2 / g BET surface area, and

[0308] b.0.01g / cm 3 Up to 0.3 g / cm 3 For example, at 0.02 g / cm 3 Up to 0.2 g / cm 3 Within the range, preferably 0.03 g / cm³. 3 Up to 0.15 g / cm 3 Within the range, it is further preferred to be within 0.1 g / cm³. 3 Up to 0.2 g / cm 3 Within the range or at 0.05 g / cm 3 Up to 0.1 g / cm 3 The packing density within the range.

[0309] c. Carbon content less than 100 ppm, for example less than 50 ppm or less than 30 ppm, particularly preferably in the range of 1 ppb to 20 ppm;

[0310] d. Less than 500 ppm, for example less than 300 ppm or less than 150 ppm, especially chlorine content in the range of 1 ppb to 80 ppm;

[0311] e. Aluminum content less than 200 ppb, for example in the range of 1 ppb to 100 ppb, and particularly preferably in the range of 1 ppb to 80 ppb;

[0312] f. The total content of atoms other than Si, O, H, C and Cl is less than 5 ppm, for example less than 2 ppm, and particularly preferably in the range of 1 ppb to 1 ppm.

[0313] g. At least 70% by weight of the powder particles have a primary particle size in the range of 10 nm to 100 nm, for example in the range of 15 nm to less than 100 nm, particularly preferably in the range of 20 nm to less than 100 nm;

[0314] h. at 0.001 g / cm 3 Up to 0.3 g / cm 3 Within a range, for example, at 0.002 g / cm³ 3 Up to 0.2 g / cm 3 Or 0.005g / cm3 Up to 0.1 g / cm 3 Within the range, preferably 0.01 g / cm³. 3 Up to 0.06 g / cm 3 Within the range, it is preferred to be within 0.1 g / cm³. 3 Up to 0.2 g / cm 3 Within the range, or at 0.15 g / cm 3 Up to 0.2 g / cm 3 Filling density within the range;

[0315] i. Residual moisture content of less than 5% by weight, for example, in the range of 0.25% by weight to 3% by weight, and particularly preferably in the range of 0.5% by weight to 2% by weight;

[0316] j. A particle size distribution D in the range of 1 μm to 7 μm, for example in the range of 2 μm to 6 μm or in the range of 3 μm to 5 μm, particularly preferably in the range of 3.5 μm to 4.5 μm. 10 ;

[0317] k. A particle size distribution in the range of 6 μm to 15 μm, for example, in the range of 7 μm to 13 μm or in the range of 8 μm to 11 μm, particularly preferably in the range of 8.5 μm to 10.5 μm. 50 ;

[0318] l. A particle size distribution D in the range of 10 μm to 40 μm, for example, in the range of 15 μm to 35 μm, and particularly preferably in the range of 20 μm to 30 μm. 90 ;

[0319] Or a combination of two or more of the features a to l;

[0320] The weight percentages, ppm, and ppb are based on the total weight of the silica powder in each case.

[0321] The silica powder contains silica. Preferably, in each case, the silica powder contains more than 95% by weight, for example more than 98% by weight, or more than 99% by weight, or more than 99.9% by weight, based on the total weight of the silica powder. Particularly preferably, the silica powder contains more than 99.99% by weight, based on the total weight of the silica powder.

[0322] In each case, based on the total weight of the silica powder, the silica powder preferably has an content of less than 5 ppm, for example less than 2 ppm, and particularly preferably less than 1 ppm of atoms other than Si, O, H, C, and Cl. However, the silica powder typically contains at least 1 ppb of atoms other than Si, O, H, C, and Cl. Atoms other than Si, O, H, C, and Cl may exist, for example, as elements, ions, or as part of molecules, ions, or complexes.

[0323] Based on the number of powder particles, at least 70% of the silica powder particles preferably have a primary particle size of less than 100 nm, for example, in the range of 10 nm to 100 nm or 15 nm to 100 nm, and particularly preferably in the range of 20 nm to 100 nm. The primary particle size is determined by scanning electron microscopy (REM) as described in the "Test Methods" section.

[0324] Based on the number of powder particles, at least 75% of the silica powder particles preferably have a primary particle size of less than 100 nm, for example in the range of 10 nm to 100 nm or 15 nm to 100 nm, and particularly preferably in the range of 20 nm to 100 nm.

[0325] Based on the number of powder particles, at least 80% of the silica powder particles preferably have a primary particle size of less than 100 nm, for example in the range of 10 nm to 100 nm or 15 nm to 100 nm, and particularly preferably in the range of 20 nm to 100 nm.

[0326] Based on the number of powder particles, at least 85% of the silica powder particles preferably have a primary particle size of less than 100 nm, for example in the range of 10 nm to 100 nm or 15 nm to 100 nm, and particularly preferably in the range of 20 nm to 100 nm.

[0327] Based on the number of powder particles, at least 90% of the silica powder particles preferably have a primary particle size of less than 100 nm, for example, in the range of 10 nm to 100 nm or 15 nm to 100 nm, and particularly preferably in the range of 20 nm to 100 nm.

[0328] Based on the number of powder particles, at least 95% of the silica powder particles preferably have a primary particle size of less than 100 nm, for example in the range of 10 nm to 100 nm or 15 nm to 100 nm, and particularly in the range of 20 nm to 100 nm.

[0329] Silica powder preferably has a particle size of 20m 2 / g to 35m 2 / g, for example 25m 2 / g to 35m2 / g, or 25m 2 / g to 30m 2 Specific surface area (BET surface area) within the range of / g. BET surface area is calculated according to DIN 66132 using the Brunauer, Emmett and Teller (BET) method based on gas absorption at the surface area to be measured.

[0330] The silica powder preferably has a pH value of less than 7, for example, in the range of 3 to 6.5, 3.5 to 6, or 4 to 5.5, and particularly preferably in the range of 4.5 to 5. The pH value can be determined by means of a single-bar measuring electrode (4% silica powder in water).

[0331] The silica powder preferably has the characteristic combination a. / b. / c. or a. / b. / f. or a. / b. / g., more preferably has the characteristic combination a. / b. / c. / f. or a. / b. / c. / g. or a. / b. / f. / g., and particularly preferably has the characteristic combination a. / b. / c. / f. / g.

[0332] The silica powder preferably has the characteristic combination a. / b. / c., wherein the BET surface area is 20m². 2 / g to 35m 2 Within the range of / g, the bulk density is in the range of 0.05g / ml to 0.3g / ml and the carbon content is less than 35ppm.

[0333] The silica powder preferably has the characteristic combination a. / b. / f., wherein the BET surface area is 20m². 2 / g to 35m 2 The bulk density is in the range of 0.05 g / ml to 0.3 g / ml, and the total content of metals other than aluminum is in the range of 1 ppb to 1 ppm.

[0334] The silica powder preferably has the characteristic combination a. / b. / g., wherein the BET surface area is 20m². 2 / g to 35m 2 The bulk density is in the range of 0.05 g / ml to 0.3 g / ml, and at least 70% by weight of the powder particles have a primary particle size in the range of 20 nm to less than 100 nm.

[0335] The silica powder is further preferably characterized by the combination a. / b. / c. / f., wherein the BET surface area is 20m². 2 / g to 35m 2Within the range of / g, the bulk density is in the range of 0.05g / ml to 0.3g / ml, the carbon content is less than 40ppm and the total content of metals other than aluminum is in the range of 1ppb to 1ppm.

[0336] The silica powder is further preferably characterized by the combination a. / b. / c. / g., wherein the BET surface area is 20m². 2 / g to 35m 2 Within the range of / g, the bulk density is in the range of 0.05g / ml to 0.3g / ml, the carbon content is less than 40ppm, and at least 70% by weight of the powder particles have a primary particle size in the range of 20nm to less than 100nm.

[0337] The silica powder is further preferably characterized by the combination a. / b. / f. / g., wherein the BET surface area is 20m². 2 / g to 35m 2 The powder has a bulk density in the range of 0.05 g / ml to 0.3 g / ml, a total metal content other than aluminum in the range of 1 ppb to 1 ppm, and at least 70% by weight of the powder particles have a primary particle size in the range of 20 nm to less than 100 nm.

[0338] Silica powder is particularly preferred to have the characteristic combination a. / b. / c. / f. / g., wherein the BET surface area is 20 2 / g to 35m 2 The powder has a bulk density in the range of 0.05 g / ml to 0.3 g / ml, a carbon content of less than 40 ppm, a total metal content other than aluminum in the range of 1 ppb to 1 ppm, and at least 70% by weight of the powder particles have a primary particle size in the range of 20 nm to less than 100 nm.

[0339] Steps i.)-iv.) of the first objective of this invention are interpreted as follows:

[0340] i.) Provide silica particles as powder and provide liquid;

[0341] ii.) Forming a slurry containing the liquid and the silica particles;

[0342] iii.) The slurry is treated with ultrasound to obtain a precursor suspension;

[0343] iv.) Pass at least a portion of the precursor suspension through at least a first multi-stage filtration device.

[0344] The first multi-stage filtration device has at least a first filtration stage, a second filtration stage, and a third filtration stage.

[0345] Each filtration stage contains at least one filter.

[0346] The second filter stage is arranged downstream of the first filter stage, and the third filter stage is arranged downstream of the second filter stage.

[0347] The first filtration stage has a filtration fineness of 5 μm or greater.

[0348] The second filtration stage has a filtration fineness in the range of 0.5 μm to 5 μm.

[0349] The third filtration stage has a filtration fineness of 1 μm or less, and

[0350] The separation rate of the first filtration stage is 50% or higher, the separation rate of the second filtration stage is 95% or higher, and the separation rate of the third filtration stage is 99.5% or higher, wherein the separation rates are determined according to ISO 16889 and based on the filter in each case.

[0351] The filtration fineness refers to the minimum particle size retained by the filter.

[0352] Additional filter stages can be set between the first, second, and third filter stages.

[0353] For the purposes of this invention, liquid means a substance or mixture of substances that is liquid at a pressure of 1013 hPa and a temperature of 20°C.

[0354] For the purposes of this invention, "slurry" means a mixture of at least two substances, wherein, under the conditions considered herein, the mixture has at least one liquid and at least one solid. During the method, a slurry and a precursor suspension are formed. The precursor suspension is also a slurry, although it is treated with ultrasound as described in step iii.). In the context of the use of the terms "slurry" or "precursor suspension" below, i.e., the general use of the term "slurry," the description may apply to slurry, precursor suspension, or both. This can be justified on the grounds that when a slurry is treated with ultrasound to obtain a precursor suspension, the treatment does not alter all of the following characteristics, or if one characteristic changes, that characteristic remains within the generally described characteristics.

[0355] In principle, a suitable liquid is any substance and mixture of substances known to those skilled in the art and suitable for the purposes of this invention. A preferred liquid is selected from the group consisting of organic liquids and water. The silica powder in the liquid is preferably dissolved in an amount less than 0.5 g / L, more preferably less than 0.25 g / L, and particularly preferably less than 0.1 g / L, where g / L represents the number of grams of silica powder per liter of liquid.

[0356] Polar solutions are preferably suited as liquids. They can be organic liquids or water. Liquids are preferably selected from the group consisting of: water, methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, and mixtures of more than one thereof. Water is particularly preferred as a liquid. Particularly preferred is that the liquid contains distilled water or deionized water, for example, water of "maximum purity," having a conductivity of <0.2 μS / cm.

[0357] The powder is preferably formed from silica particles and a liquid slurry. The silica particles are practically insoluble in the liquid at room temperature, but can be added to the liquid in a high weight proportion while maintaining the slurry. The slurry is obtained by mixing its components.

[0358] Silica particle powder and liquid can be mixed in any desired manner. For example, powder can be added to liquid or liquid can be added to powder. The mixture can be stirred during or after addition. Particularly preferred is that the mixture is stirred during and after addition. The term "stirring" includes shaking and agitation or a combination of both. Powder can preferably be added to liquid while stirring it. It is also preferred to add a portion of powder to liquid, wherein the mixture thus obtained is stirred, and then the mixture is mixed with the remaining portion of powder. Alternatively, a portion of liquid can be added to powder, wherein the mixture thus obtained is stirred, and then mixed with the remaining portion of liquid.

[0359] Silica powder and liquid are mixed to obtain a slurry. The slurry is preferably a suspension in which silica particles are uniformly distributed in the liquid. The term "uniformly" means that, in each case, based on the total amount of slurry, the density and composition of the slurry at any point varies by no more than 10% relative to the average density and average composition. As previously stated, the uniform distribution of silica particles in the liquid can be achieved or maintained, or achieved and maintained, by agitating the silica particles as described above. The precursor suspension is also a suspension having the characteristics just described.

[0360] The weight of the slurry and precursor suspension is preferably in the range of 1000 g / L to 2000 g / L, for example, in the range of 1200 g / L to 1900 g / L or 1300 g / L to 1800 g / L, and particularly preferably in the range of 1400 g / L to 1700 g / L. The weight per liter is determined by weighing a calibrated container.

[0361] According to one embodiment, the slurry has at least one, for example at least two, at least three, or at least four, and particularly preferably at least five of the following characteristics:

[0362] A.) The slurry has a solids content of at least 20% by weight, for example, in the range of 20% to 70% by weight, or in the range of 30% to 50% by weight, or in the range of 55% to 75% by weight, particularly preferably in the range of 60% to 70% by weight, in each case based on the total weight of the slurry;

[0363] B.) The slurry has a pH value in the range of 3 or greater, for example, greater than 4, or in the range of 4.5 to 8 or 4.5 to 7, wherein the pH value is determined using 4% by weight of the slurry;

[0364] C.) In 4% by weight of the slurry, according to DIN ISO 13320-1, at least 90% of the silica particles in the slurry have a particle size in the range of 1 nm to <100 μm, for example, in the range of 200 nm to 700 nm.

[0365] D.) Chlorine content of 500 ppm or lower;

[0366] E.) The content of atoms other than Si, O, H, C, and Cl does not exceed 5 ppm;

[0367] F.) The slurry is vibrated and coagulated;

[0368] G.) The slurry is transported in contact with the plastic surface;

[0369] The slurry described in H.) is sheared;

[0370] I.) The slurry has a temperature greater than 0°C, preferably in the range of 5°C to 35°C;

[0371] J.) According to DIN 53019-1 (5 rpm, 30% by weight), the slurry has a viscosity in the range of 500 mPas to 2000 mPas, for example in the range of 600 mPas to 1700 mPas, and particularly preferably in the range of 650 mPas to 1350 mPas.

[0372] K.) In 4% by weight of the slurry, according to DIN ISO 13320-1, at least 5% of the silica particles in the slurry have a particle size in the range of >10 μm.

[0373] According to another embodiment, the precursor suspension also has at least one of the above-mentioned features A.)-K.), for example, at least two, at least three, or at least four, and particularly preferably at least five.

[0374] The silica particles in 4% by weight of the aqueous slurry that have not been pretreated by depolymerization preferably have a particle size D in the range of 50 nm to 250 nm, particularly preferably in the range of 100 nm to 150 nm.10 The silica particles in 4% by weight of the aqueous slurry preferably have a particle size D in the range of 100 nm to 400 nm, particularly preferably in the range of 200 nm to 250 nm. 50 The silica particles in the 4% by weight aqueous slurry preferably have a particle size D in the range of 200 nm to 600 nm, particularly preferably in the range of 350 nm to 400 nm. 90 Particle size was determined according to DIN ISO 13320-1. The particle size D... 10 D 50 Or D 90 Or a combination of two or more of them can also be used for precursor suspensions.

[0375] Particle size refers to the size of primary particles in silica powder, particles aggregated as silica particles in slurries, precursor suspensions, or silica granules. Average particle size refers to the arithmetic mean of all particle sizes of the substance. D 50 The value indicates that, based on the total number of particles, 50% of the particles are smaller than the stated value. D 10 The value indicates that, based on the total number of particles, 10% of the particles are smaller than the stated value. D 90 The value indicates that, based on the total number of particles, 90% of the particles are smaller than the stated value. Particle size is determined according to ISO 13322-2:2006-11 using a dynamic image analysis procedure.

[0376] The term "isoelectric point" refers to the pH value at which the zeta potential is assumed to be 0. The zeta potential is determined according to ISO 13099-2:2012.

[0377] The pH value of the slurry is preferably set within the range described above. For example, a substance such as NaOH or NH3 can be added to the aqueous slurry solution to adjust the pH value, and the slurry can be frequently agitated. The pH value described for the slurry can also be applied to the pH value of the precursor suspension.

[0378] In step iii.) below, the slurry is ultrasonically treated to obtain a precursor suspension. This is done because slurries always accumulate solid particles present in the slurry to form larger build-ups (also called agglomerates), which are ultrasonically treated to deagglomerate them. The term "deagglomeration" refers to measures and processes that help dissolve the agglomerates (also referred to here as build-ups) of particles in the suspension or slurry and break down the particles. Other methods exist for deagglomerating such build-ups in slurries, such as treating the slurry in a ball mill. Here, typically stainless steel balls move through the liquid, generating kinetic energy, which, when such balls are found in the particle build-ups they apply, causes these balls to deagglomerate the particles in turn. When preparing high-purity substances, the use of a ball mill is considered disadvantageous because the movement of the balls and their contact with the grinding vessel always grinds the material from the balls or from the grinding vessel. This is usually metallic: when preparing high-purity substances, because it contaminates the high-purity substances, additional cleaning steps and / or reprocessing must be used on the milled slurry to remove it from the slurry and / or its subsequent products, which is expensive and / or time-consuming.

[0379] For ultrasonic treatment, in principle any method and any ultrasonic source known to a person skilled in the art and that appears suitable for this application may be used.

[0380] In this context, ultrasound is a sound wave with a peak frequency in the range of 20 kHz to 100 kHz. This can also be a single-frequency sound wave or a bandwidth sound wave. In the latter case, at least 60% of the ultrasound frequency used within a certain range is pressurized at ±10 Hz of the peak frequency.

[0381] In another embodiment, the slurry is ultrasonically treated for at least 10 seconds, such as at least 20 seconds, or at least 40 seconds, or at least 60 seconds, 120 seconds, 180 seconds or 240 seconds.

[0382] In another embodiment, the slurry is ultrasonically treated for up to 1000 seconds, for example up to 500 seconds, or up to 200 seconds, or up to 100 seconds, 50 seconds, or 20 seconds.

[0383] In another embodiment, the slurry is ultrasonically treated for a period of time ranging from 10 to 1800 seconds, such as 30 to 1000 seconds, or 30 to 600 seconds, or 40 to 300 seconds.

[0384] The power density used in ultrasound is obtained by dividing the electrical power consumed by the ultrasonic source by the volume of the slurry. In another embodiment, the ultrasonic source used is an ultrasonic generator, a stirred ball mill, or a combination of both.

[0385] In another embodiment, the temperature of the slurry during ultrasonic treatment is in the range of 5°C to 45°C, for example, between 10°C and 40°C, or between 15°C and 40°C.

[0386] In another embodiment, the ultrasonic power density applied to the slurry is less than 600 W / l, for example less than 450 W / l, or about 300 W / l, based on the volume of the slurry. The power density is typically not less than 100 W / l.

[0387] In one embodiment, the ultrasonic power density is in the range of 400 W / l to 500 W / l, and the processing time is in the range of 10 seconds to 90 seconds.

[0388] In another embodiment, the ultrasonic power density is in the range of 300W / l to 400W / l and the processing time is in the range of 90 seconds to 250 seconds.

[0389] In the depolymerized 4% by weight slurry, preferably at least 90% of the silica particles have a particle size in the range of 1 nm to 1 μm, for example, in the range of 30 nm to 600 nm or 100 nm to 300 nm, according to DIN ISO 13320-1, wherein the particle size is measured in a silica suspension with a solid content of 4% by weight.

[0390] In the depolymerized 4% by weight slurry, less than 1% of silica particles with a particle size greater than 1 μm are preferred according to DIN ISO 13320-1, wherein the particle size is measured in a silica suspension with a solid content of 4% by weight.

[0391] In step iv.) below, at least a portion of the precursor suspension is passed through a first multi-stage filtration device. After passing through the multi-stage filtration device, the silica suspension is obtained as filtrate. The first multi-stage filtration device has at least a first filtration stage, a second filtration stage, and a third filtration stage. The first multi-stage filtration device may have additional filtration stages, such as a fourth filtration stage, and if necessary, a fifth filtration stage, and if necessary, a sixth filtration stage. The filtration stages in the multi-stage filtration device are arranged in a specific order. The filtration stages are numbered in the downstream direction. This means that the precursor suspension first flows through the first filtration stage, then downstream through the second filtration stage, and so on. Multiple filter arrangements are also conceivable, in which different amounts of suspension pass through filters arranged more or less simultaneously adjacent to each other. Arranging multiple filters adjacent to each other within a filtration stage can increase the service life of the filtration stage or the throughput through the filtration stage, or both. Furthermore, additional filtration stages may be provided between the first and second filtration stages, or between the second and third filtration stages, which will not be further described here.

[0392] Each filtration stage includes at least one filter. A single filter can be placed within a filtration stage; multiple filters can also be placed. These filters are typically arranged adjacent to each other. In this case, the multiple filters used usually have the same characteristic data. As mentioned above, multiple filters can be placed adjacent to each other to distribute the flow within the filtration stage: this typically increases the operating life or throughput of the filtration stage, or both.

[0393] The first filtration stage has a filtration fineness of 5 μm or larger, for example, 5 μm to 15 μm, or about 10 μm, or about 15 μm.

[0394] The second filtration stage has a filtration fineness in the range of 0.5 μm to 5 μm, for example, in the range of 0.5 μm to 2 μm, or about 1 μm, or about 2 μm.

[0395] The third filtration stage has a filtration fineness of 1 μm or smaller, such as 1 μm or 0.5 μm.

[0396] At least one filtration stage selected from the first, second, and third filtration stages has a separation rate of 99.5% or higher, such as 99.8% or 99.9%.

[0397] Filtration fineness refers to the smallest particle size that a filter with a given efficiency can filter. Filtration fineness will also be referred to as "x" below.

[0398] Separation rate or filtration rate ε x In all cases, as stated in ISO 16889:2008. According to that standard, β x Value in N x and N h The quotient is determined, where N x N is the number of particles upstream of the filter. h = Number of particles downstream of the filter, where x is the filtration fineness. Filtration fineness is the particle size, in μm, used to determine the separation rate. Separation rate, or ε x Then it is (β) x -1) / β x .

[0399] For example, for a suspension of 400 particles, the separation rate ε is 75%. 10 This means that if the suspension has a particle size of 10 μm or larger per unit volume downstream of the filter, then one out of 100 particles will have a particle size of 10 μm or larger per unit volume downstream of the filter. In this example, 75% of the particles removed from the suspension have a particle size of 10 μm or larger.

[0400] By analogy with the definitions of separation rate and filtration fineness of a single filter, the corresponding data for a filtration stage containing one or more individual filters can be obtained using the above range and preferred embodiments.

[0401] The first filtration device may have at least one, more than one, or all of the following features:

[0402] (a) The first filtration stage has a separation rate of 90% or lower, such as 85%, 80% or 75%, or 80% to 99.9%, or 80% to 95%;

[0403] (b) The first filtration stage has a filtration fineness in the range of 5 μm or larger, 5 μm to 25 μm, or 5 μm to 15 μm, for example, 10 μm or 5 μm;

[0404] (c) The second filtration stage has a separation rate of 80% or higher, such as 95% or higher, such as 98%, 99%, 99.9% or 99.99%, or in the range of 80% to 99.9%, or 80% to 95%;

[0405] (d) The second filtration stage has a filtration fineness of 0.5 μm or greater, for example, 0.5 μm to 10 μm, or 0.5 μm to 2 μm, for example, 0.5 μm, 1.0 μm, 1.5 μm or 2.0 μm;

[0406] (e) The third filtration stage has a separation rate of 80% or higher, such as 99.5% or higher, such as 99.9% or 99.99%, or in the range of 80% to 99.9%, or in the range of 95% to 99.9%;

[0407] (f) The first filtration stage has a filtration fineness in the range of 0.5 μm or higher, for example, in the range of 0.5 μm to 10 μm, or 0.5 μm to 3 μm, or 0.5 μm to 1 μm;

[0408] Or a combination of two or more of features (a) to (f), wherein any combination of values ​​stated by way of example is preferred. In one embodiment, a combination of all features (a) to (f) is advantageous, for example, F1.3 in Table A below.

[0409] In a preferred embodiment, the first filtration stage has a filtration fineness of 5 μm or greater, for example, from 5 μm to 25 μm, and a separation rate in the range of 80% to 99.9%, preferably from 80% to 95%.

[0410] In another embodiment, the second filtration stage has a filtration fineness of 0.5 μm or greater, for example, in the range of 0.5 μm to 10 μm, and a separation rate in the range of 80% to 99.9%, preferably 80% to 95%, preferably 95% to 99.9%.

[0411] In another embodiment, the third filtration stage has a filtration fineness of 0.5 μm or greater, for example, in the range of 0.5 μm to 10 μm, and a separation rate in the range of 80% to 99.9%, preferably 95% to 99.9%.

[0412] According to another example, the features of the first filtering device may be a combination of the following features:

[0413] Table A

[0414]

[0415] In another embodiment, the first multi-stage filtration device includes at least one depth filter. In this context, the term "depth filter" means a filter in which particles to be separated are retained in a section within the filter, wherein a filter cake is typically not formed when the filter is operated. On the other hand, with zone filters or surface filters, particles to be separated are separated at the boundaries of the surface filter, and a filter cake accumulates when the filter is operated. The first multi-stage filtration device may also include multiple depth filters. All filters used in the first multi-stage filtration device may also be depth filters.

[0416] In another embodiment, at least one additional, preferably multi-stage filtration device is used downstream of the first multi-stage filtration device; similarly, two, three, four, five, or up to ten or more multi-stage filtration devices are arranged in series downstream.

[0417] In another embodiment, at least the second multi-stage filtration device is provided with a depth filter.

[0418] In another embodiment, the second filtration stage of the first filtration device includes at least one first filter with a separation rate of 90% or less and at least one additional filter with a separation rate of 95% or higher.

[0419] In another embodiment, the first multistage filtration device has a working life of at least 100 liters, such as 150 liters or more, or 250 liters or more, or 500 liters, or 800 liters or more, or 1000 liters or more, in each case based on the volume of the precursor suspension filtered by the first multistage filtration device.

[0420] In another embodiment, the optional second multistage filtration unit has a working life of at least 100 liters, such as 150 liters or more, or 250 liters or more, or 500 liters, in each case based on the volume of the precursor suspension filtered by the second filtration unit.

[0421] Regarding filter units, "operating life" refers to the volume of suspension that can pass through the filter unit before it becomes clogged. Clogging can be identified by an increase in pressure upstream of the filter to at least 1.5 times the pressure of a new filter in use, while maintaining pumping performance. If a filter becomes clogged, the operating stage must be shut down and one or more clogged filters must be cleaned or replaced.

[0422] In another embodiment, the slurry contains less than 5% by weight of additives, less than 2% by weight, for example, 0% by weight (no) additives, particularly stabilizing additives, with the weight percentages based on the total weight of the slurry. Typically, the slurry contains at least 0.1% by weight, for example, in the range of 0.1% to 5% by weight of additives, with the weight percentages based on the total weight of the slurry. During the filtration process, the additive content typically does not change or changes almost no. Therefore, both the resulting precursor suspension and the silica suspension have the content of stabilizing additives as described for the slurry.

[0423] In another embodiment, the silica suspension obtained by this method has at least one, for example at least two, at least three, or at least four, and particularly preferably at least five of the following characteristics:

[0424] A. The silica suspension was agglutinated under the test conditions, which means at temperatures below 45°C and solid concentrations ranging from 20% to 70% by weight.

[0425] B. At least 90% of the silica particles in the silica suspension have a particle size in the range of 1 nm to <10 μm, for example, in the range of 1 nm to 1 μm, 30 nm to 600 nm, or 100 nm to 300 nm, or 200 nm to 300 nm, wherein the particle size is determined according to DIN ISO 13320-1 in a silica suspension with a solid content of 4% by weight.

[0426] C. The silica suspension has a pH value in the range of 3 or greater, for example, greater than 4, or in the range of 4.5 to 8 or 4.5 to 7, wherein the pH value is determined by 4% by weight of the silica suspension;

[0427] D. Chlorine content less than 500 ppm, 350 ppm or less, or 200 ppm or less;

[0428] E. Aluminum content less than 200 ppb, for example in the range of 1 ppb to 100 ppb, and particularly preferably in the range of 1 ppb to 80 ppb;

[0429] F.5 ppm or less of atoms other than Si, O, H, C, and Cl;

[0430] G. The silica suspension has a temperature greater than 0°C, preferably in the range of 5°C to 35°C;

[0431] H. According to DIN 53019-1 (5 rpm, 30% by weight), silica suspensions have a viscosity in the range of 500 mPas to 2000 mPas, for example in the range of 600 mPas to 1700 mPas, and particularly preferably in the range of 650 mPas to 1350 mPas.

[0432] I. The silica particles in the silica suspension are less than 1% having a particle size greater than 1 μm, wherein the particle size in the silica suspension with a solid content of 4% by weight is measured according to DIN ISO 13320-1.

[0433] The weight percentages (%), ppm, and ppb are based on the total amount of silica particles in the suspension.

[0434] Preparation of silica particles

[0435] Then step v.) forms silica particles, wherein the silica suspension from step iv.) is further processed. In one embodiment, a silicon component other than silica may be added in this step.

[0436] The particle size of silica particles is larger than that of silica particles present in silica suspension.

[0437] In principle, silica particles can be prepared by any and all methods known to the technicians to increase particle size.

[0438] The particle size of silica particles is larger than that of silica powder, and also larger than that of silica particles in the silica suspension mentioned above.

[0439] The particle size of silica particles is larger than that of silica powder. Preferably, the particle size of silica particles is 500 to 50,000 times larger than that of silica powder, for example, 1,000 to 10,000 times larger, and particularly preferably 2,000 to 8,000 times larger.

[0440] At least 90%, for example at least 95% by weight or at least 98% by weight, particularly preferably at least 99% by weight or more of the silica particles formed in step iv.), are preferably made from pyrolytic silica powder, in each case based on the total weight of the silica particles.

[0441] The processing preferably forms fine silica particles, wherein the fine particles have a spherical morphology; preferably, the processing further includes spray granulation or roller granulation.

[0442] Powder refers to dry solids with a primary particle size ranging from 1 nm to less than 100 nm.

[0443] Silica particles can be obtained by granulating silica powder. Typically, silica particles have a particle size of 3 μm. 2 / g or greater BET surface area and less than 1.5g / cm² 3 The density of silica particles. The term "granulation" refers to the process of converting powder particles into fine particles. In granulation, agglomerates of multiple silica particles are formed, which are larger agglomerates called "silica fine particles." These are often also referred to as "silica particulate particles" or "particle particles." The fine particles collectively form granules, such as silica particles forming "silica granules." Silica granules have a larger particle size than silica powder.

[0444] The granulation method for converting powder into granules will be explained in more detail below.

[0445] In this document, the term silica particles refers to silica particles that can be obtained by crushing silica mass, particularly quartz glass. Silica particles typically have a density greater than 1.2 g / cm³. 3 For example, at 1.2 g / cm³ 3 Up to 2.2 g / cm 3 Within the range, and particularly preferred at approximately 2.2 g / cm³. 3 The density; and according to DIN ISO 9277:2014-01, the BET surface area of ​​silica particles is typically less than 1 m². 2 / g.

[0446] In principle, silica powder can be any and all silica particles known to a person skilled in the art as suitable, especially silica particles described in step i.).

[0447] The term "particle size" or "grain diameter" refers to the area of ​​a circle with the equivalent diameter x, expressed by the following formula. Ai The diameter of the obtained particles: Here, Ai refers to the area of ​​the particle considered through image analysis. Suitable determination methods are, for example, ISO 13322-1:2014 or ISO 13322-2:2009. Comparative statements, such as "larger particle size," always mean that the value cited was determined by the same method.

[0448] The fine particles of silica preferably have a spherical morphology. "Spherical morphology" means that the particles have a round to elliptical shape. The fine particles of silica preferably have an average sphericity in the range of 0.7 to 1.3 SPHT3, for example, in the range of 0.8 to 1.2 SPHT3, and particularly preferably in the range of 0.85 to 1.1 SPHT3. The SPHT3 characteristics are described in the test methods.

[0449] The fine particles of silica preferably have an average symmetry in the range of 0.7 to 1.3 Symm³, for example, an average symmetry in the range of 0.8 to 1.2 Symm³, and particularly preferably an average symmetry in the range of 0.85 to 1.1 Symm³. The average symmetry characteristic Symm³ is described in the test method.

[0450] Granulation

[0451] Silica particles are obtained by granulating silica powder. The term "granulation" refers to the process of transforming powder particles into fine particles. In granulation, multiple silica particles aggregate to form larger agglomerates called "silica fine particles." These are often also referred to as "silica granular particles" or "granular particles." The particles collectively form granules, such as silica fine particles forming "silica granules."

[0452] In this case, in principle, any granulation method known to a technician and appearing suitable for granulating silica powder can be selected. Granulation methods can be categorized into agglomeration granulation and compression granulation, and further divided into wet granulation methods and dry granulation methods. Known methods include roller granulation on a granulation plate, spray granulation, centrifugal atomization, floating bed granulation, cryogenic granulation, and granulation methods using a granulation mill, compaction, roller pressing, briquetting, crusting, and extrusion.

[0453] Preferably, during processing, silica particles with a spherical morphology are formed; wherein this processing is also preferably carried out by spray granulation or roller granulation. More preferably, the silica particles with a spherical morphology also have no more than 50% fine particles, preferably no more than 40% fine particles, even more preferably no more than 20% fine particles, more preferably between 0% and 50%, between 0% and 40%, or between 0% and 20%, or between 10% and 50%, between 10% and 40%, or between 10% and 20% non-spherical fine particles, the percentages being based on the total number of fine particles in each case. The spherical fine particles have the SPHT3 value already mentioned in these specifications.

[0454] Spray granulation

[0455] According to a preferred embodiment of step v.), silica particles are formed by spray granulation of a silica suspension. Spray granulation is also known as spray drying.

[0456] Spray drying is preferably carried out in a spray tower. In spray drying, a silica suspension is pressurized at a high temperature. The pressurized silica suspension is then depressurized through nozzles and sprayed into the spray tower. Instantly dried droplets are then formed, initially forming dried microparticles (“microbes”). The microparticles and the gas flow acting on them form a fluidized bed, thus remaining in suspension and allowing the formation of surfaces for drying other droplets.

[0457] The nozzle through which the silica suspension is sprayed into the spray tower preferably forms an inlet into the interior of the spray tower.

[0458] During spraying, the nozzle preferably has a contact surface with the silica suspension. The term "contact surface" refers to the nozzle surface that comes into contact with the silica suspension when the suspension is sprayed. Typically, at least a portion of the nozzle is formed as a tube through which the silica suspension passes during spraying, thus the interior of the hollow tube comes into contact with the silica suspension.

[0459] The contact surface preferably comprises glass, plastic, or a combination thereof. Glass is particularly preferred, especially quartz glass. Plastic is also preferred. In principle, all suitable plastics known to those skilled in the art are those that are stable at the process temperature and do not release any foreign atoms into the silica suspension. Preferred plastics are polyolefins, such as homopolymers or copolymers containing at least one olefin, particularly preferably homopolymers or copolymers containing polypropylene, polyethylene, polybutadiene, or combinations thereof. Preferably, the contact surface comprises glass, plastic, or a combination thereof, for example selected from the group consisting of quartz glass and polyolefins, particularly preferably selected from the group consisting of quartz glass and homopolymers or copolymers containing polypropylene, polyethylene, polybutadiene, or combinations thereof. Preferably, the contact surface does not contain any metals, particularly tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium, or manganese.

[0460] In principle, the contact surface and other components of the nozzle may be composed of the same or different materials. Preferably, the other components of the nozzle contain the same material as the contact surface. The other components of the nozzle may also contain different materials. For example, the contact surface may be coated with a suitable material, such as glass or plastic.

[0461] Based on the total weight of the nozzle, more than 70% by weight, for example, more than 75% by weight, or more than 80% by weight, or more than 85% by weight, or more than 90% by weight, or more than 95% by weight, particularly preferably more than 99% by weight, the nozzle is formed of elements selected from the group consisting of glass, plastic or a combination of glass and plastic.

[0462] Preferably, the nozzle comprises a nozzle metal sheet. The nozzle metal sheet is preferably made of glass, plastic, or a combination of glass and plastic. Preferably, the nozzle metal sheet is formed of glass, preferably quartz glass. Preferably, the nozzle metal sheet is formed of plastic. Preferred plastics are polyolefins, such as homopolymers or copolymers containing at least one olefin, particularly preferred are homopolymers or copolymers containing polypropylene, polyethylene, polybutadiene, or combinations thereof. Preferably, the nozzle metal sheet does not contain any metals, particularly tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium, or manganese.

[0463] Preferably, the nozzle comprises a screw twister. The screw twister is preferably formed of glass, plastic, or a combination of glass and plastic. The screw twister is preferably formed of glass, particularly quartz glass. The screw twister is also preferably formed of plastic. Preferred plastics are polyolefins, such as homopolymers or copolymers containing at least one olefin, particularly preferably homopolymers or copolymers containing polypropylene, polyethylene, polybutadiene, or combinations thereof. Preferably, the nozzle metal sheet does not contain any metals, particularly tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium, or manganese.

[0464] The nozzle may also include additional components. Other preferred components are nozzle bodies, particularly nozzle bodies comprising a screw twister and nozzle bodies surrounding a nozzle metal sheet, cross-sections, and an impact metal plate. The nozzle preferably includes one or more of these additional components, particularly all of them. These additional components may, in principle, independently comprise any other materials known to those skilled in the art suitable for this purpose, such as metal-based materials, glass, or plastics. The nozzle body is preferably formed of glass, particularly quartz glass. The additional components are preferably made of plastic. Preferred plastics are polyolefins, such as homopolymers or copolymers containing at least one olefin, particularly preferably homopolymers or copolymers containing polypropylene, polyethylene, polybutadiene, or combinations thereof. Preferably, the nozzle metal sheet does not contain any metals, particularly tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium, or manganese.

[0465] The spray tower preferably has a gas inlet and a gas outlet. The gas inlet can be used to inject gas into the interior of the spray tower, and it can be released through the gas outlet. Gas may also be injected into the spray tower via a nozzle. Similarly, the gas can be drawn out through the spray tower outlet. More preferably, gas can be fed into the spray tower via a nozzle and a gas inlet and drawn out of the spray tower via a gas outlet.

[0466] Inside the spray tower, the atmosphere is preferably air, an inert gas, at least two inert gases, or a combination of air and at least one inert gas, preferably at least two inert gases. The inert gas is preferably selected from the list of nitrogen, helium, neon, argon, krypton, and xenon. Inside the spray tower, the atmosphere is preferably air, nitrogen, or argon, with air being particularly preferred.

[0467] The atmosphere in the spray tower is preferably also part of a gas stream. The gas stream is preferably introduced into the spray tower via a gas inlet and discharged via a gas outlet. Some gas stream may also be introduced via a nozzle and discharged via a solid outlet. The gas stream may acquire other components in the spray tower, which, in the case of spray drying, may originate from a silica suspension and enter the gas stream.

[0468] The gas stream fed into the spray tower is preferably dry. "Dry gas stream" refers to gas or gas mixtures with a relative humidity below their condensation point at the temperature set within the spray tower. 100% relative humidity is equivalent to 17.5 g / m³ at 20°C. 3 The water content. It is preferable to preheat the gas to 150°C to 450°C, for example 200°C to 420°C or 300°C to 400°C, and particularly preferably a temperature in the range of 320°C to 400°C.

[0469] The temperature inside the spray tower can be preferably set. The preferred temperature inside the spray tower is up to 550°C, for example, 300°C to 500°C, and particularly preferably 320°C to 450°C.

[0470] The gas flow at the gas inlet is preferably at a temperature in the range of 150°C to 450°C, for example, 200°C to 420°C or 300°C to 400°C, and particularly preferably in the range of 320°C to 400°C.

[0471] At the solid outlet, gas outlet, or both, the released gas stream is preferably at a temperature below 170°C, for example, 50°C to 150°C, and particularly preferably 100°C to 130°C.

[0472] More preferably, the difference between the gas inlet temperature and the outlet temperature is in the range of 100°C to 330°C, for example, 150°C to 300°C.

[0473] The resulting silica particles are agglomerates of individual silica powder particles. Individual silica powder particles can still be detected in the agglomerates. The average silica particle size is preferably in the range of 10 nm to 1000 nm, for example, in the range of 20 nm to 500 nm, or 30 nm to 250 nm, or 35 nm to 200 nm, or 40 nm to 150 nm, or particularly in the range of 50 nm to 100 nm. The average particle size is determined according to DIN ISO 13320-1.

[0474] Spray drying can be carried out in the presence of excipients. In principle, any and all substances known to those skilled in the art and appearing suitable for the purposes of this invention can be used as excipients. Excipients that can be considered are, for example, so-called "binders". Examples of suitable binders are metal oxides, such as calcium oxide; metal carbonates, such as calcium carbonate; and polysaccharides, such as cellulose, cellulose ethers, starch, and starch derivatives.

[0475] For the purposes of this invention, spray drying is preferably carried out without excipients.

[0476] Some silica particles are preferably separated before, after, or both before and after removal from the spray tower. This separation can be achieved by any and all methods known to a person skilled in the art that appear suitable, such as screening or sieving.

[0477] Preferably, before removing the silica particles formed by spray drying from the spray tower, particles with a size less than 50 μm, for example less than 70 μm, and particularly preferably less than 90 μm, are screened out. Screening is preferably carried out using a cyclone separator, which is preferably arranged in the lower region of the spray tower, and particularly preferably above the spray tower outlet.

[0478] Preferably, after the silica particles are removed from the spray tower, in principle, by any and all methods known to those skilled in the art and suitable for this purpose, preferably by means of a vibrating trough, the silica particle fraction with a particle size greater than 1000 μm, for example, a particle size greater than 700 μm, and particularly preferably a particle size greater than 500 μm, is separated.

[0479] According to one embodiment, the method of spraying and drying a silica suspension into a spray tower via nozzles is characterized by at least one, such as two or three, and particularly preferably all of the following features:

[0480] a) Spray granulation in a spray tower;

[0481] b] The silica pressure at the nozzle does not exceed 40 bar, for example in the range of 1.3 bar to 20 bar, 1.5 bar to 18 bar, or 2 bar to 15 bar, or 4 bar to 13 bar, or particularly preferably in the range of 5 bar to 12 bar, wherein the pressure is absolute pressure (relative to p = 0 hPa).

[0482] c] The temperature of the droplets entering the spray tower is in the range of 10°C to 50°C, preferably in the range of 15°C to 30°C, and particularly preferably in the range of 18°C ​​to 25°C.

[0483] d] The temperature on the side of the nozzle facing the spray tower is in the range of 100°C to 450°C, for example, in the range of 250°C to 440°C, and particularly preferably in the range of 320°C to 430°C;

[0484] e] The flow rate of the silica suspension through the nozzle is 0.05 m³ / s. 3 / h to 1m 3 Within the range of / h, for example, in 0.1m 3 / h to 0.7m 3 / h or 0.2m 3 / h to 0.5m 3 Within the range of / h, it is particularly preferred to be within 0.25m. 3 / h to 0.4m 3 Within the range of / h;

[0485] f] The silica suspension has a solid content of at least 40% by weight, for example in the range of 50% to 80% by weight, or in the range of 55% to 75% by weight, particularly preferably in the range of 60% to 70% by weight, based on the total weight of the silica suspension in each case;

[0486] g] The gas flow entering the spray tower is in the range of 10 kg / min to 100 kg / min, for example, in the range of 20 kg / min to 80 kg / min or 30 kg / min to 70 kg / min, and particularly preferably in the range of 40 kg / min to 60 kg / min;

[0487] h] The temperature of the gas stream entering the spray tower is in the range of 100°C to 450°C, for example, in the range of 250°C to 440°C, and particularly preferably in the range of 320°C to 430°C;

[0488] i] The temperature of the gas stream exiting the spray tower is below 170°C;

[0489] j] The gas is selected from the group consisting of: air, nitrogen and helium or a combination of two or more thereof, preferably air;

[0490] [k] In each case, based on the total weight of the silica particles obtained by spray drying, the particles taken out of the spray tower have a residual moisture content of less than 5% by weight, for example less than 3% by weight or less than 1% by weight or in the range of 0.01% by weight to 0.5% by weight, particularly preferably in the range of 0.1% by weight to 0.3% by weight.

[0491] Based on the total weight of silica obtained by spray drying, at least 50% by weight of the sprayed particles are completed within a flight time of 1 to 100 seconds, for example, within a period of 10 to 80 seconds, and particularly preferably within a period of 25 to 70 seconds.

[0492] Based on the total weight of silica obtained by spray drying, at least 50% by weight of the sprayed particles complete a flight path of more than 20m, for example, more than 30m, or more than 50m, or more than 70m, or more than 100m, or more than 150m, or more than 200m, or in the range of 20m to 200m, or 10m to 150m, or 20m to 100m, particularly preferably in the range of 30m to 80m.

[0493] The spray tower described in n] has a cylindrical geometry;

[0494] o] The height of the spray tower is greater than 10m, for example greater than 15m, or greater than 20m, or greater than 25m, or greater than 30m, or in the range of 10m to 25m, particularly preferably in the range of 15m to 20m;

[0495] [p] Before removing the particles from the spray tower, particles smaller than 90 μm are screened out;

[0496] [q] After the particles are removed from the spray tower, it is preferable to screen out particles with a size greater than 500 μm on a vibrating trough;

[0497] The silica suspension droplets exit the nozzle at an angle of 30°-60° to the vertical direction, and particularly preferably at an angle of 45° to the vertical direction.

[0498] "Vertical" refers to the direction of the gravity vector.

[0499] The flight path refers to the path taken by silica suspended particles in the spray tower gas space from leaving the nozzle, forming fine particles, until they complete their flight and descent. The flight and descent process typically ends with the fine particles impacting the spray tower base plate or other fine particles already on the base plate, depending on which occurs first.

[0500] Flight time is the time taken for the particles to travel their flight path within a fine-particle traveling spray tower. The fine particles in the spray tower preferably have a spiral flight path.

[0501] Based on the total weight of silica particles obtained by spray drying, at least 60% by weight of the sprayed particles preferably travel an average flight path of more than 20m, for example, more than 30m, or more than 50m, or more than 70m, or more than 100m, or more than 150m, or more than 200m, or in the range of 20m to 200m, or 10m to 150m, or 20m to 100m, particularly preferably in the range of 30m to 80m.

[0502] Based on the total weight of silica particles obtained by spray drying, at least 70% by weight of the sprayed particles preferably travel an average flight path of more than 20m, for example, more than 30m, or more than 50m, or more than 70m, or more than 100m, or more than 150m, or more than 200m, or in the range of 20m to 200m, or 10m to 150m, or 20m to 100m, particularly in the range of 30m to 80m.

[0503] Based on the total weight of silica particles obtained by spray drying, at least 80% by weight of the sprayed particles preferably travel an average flight path of more than 20m, for example, more than 30m, or more than 50m, or more than 70m, or more than 100m, or more than 200m, or in the range of 20m to 200m, or 10m to 150m, or 20m to 100m, particularly preferably in the range of 30m to 80m.

[0504] Based on the total weight of silica particles obtained by spray drying, at least 90% by weight of the sprayed particles preferably travel an average flight path of more than 20m, for example, more than 30m, or more than 50m, or more than 70m, or more than 100m, or more than 150m, or more than 200m, or in the range of 20m to 200m, or 10m to 150m, or 20m to 100m, particularly preferably in the range of 30m to 80m.

[0505] Roller granulation

[0506] According to another preferred embodiment of step v.), silica particles are formed by roller granulation of a silica suspension.

[0507] Roller granulation is performed by agitating a silica suspension at a high temperature in the presence of gas. Roller granulation is preferably carried out in a stirred container equipped with a stirring device. Preferably, the stirred container rotates in the opposite direction to the stirring device. Preferably, the stirred container also has an inlet for feeding silica into the stirred container, an outlet for expelling silica particles, a gas inlet, and a gas outlet.

[0508] The silica suspension is preferably agitated by a pin-type stirring tool. A pin-type stirring tool refers to a stirring tool equipped with multiple long pins, in each case having the axial axis of the long pins coaxial with the rotation axis of the stirring tool. The pins are preferably described as coaxial circles around the rotation axis.

[0509] The silica suspension is preferably set to a pH value less than 7, for example, a pH value in the range of 2 to 6.5, and particularly preferably a pH value in the range of 4 to 6. An inorganic acid is preferably used, for example, an acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, with hydrochloric acid being particularly preferred.

[0510] The atmosphere in the stirred container is preferably selected from air, an inert gas, at least two inert gases, or a combination of air and at least one inert gas, preferably at least two inert gases. The inert gas is preferably selected from a list consisting of nitrogen, helium, neon, argon, krypton, and xenon. For example, the stirring may contain air, nitrogen, or argon, with air being particularly preferred.

[0511] The atmosphere in the stirred vessel is preferably also part of the gas stream. The gas stream in the stirred vessel is preferably introduced via a gas inlet and exited via a gas outlet. The gas stream can absorb other components in the stirred vessel: in roller pelletizing, these components can originate from the silica suspension and enter the gas stream.

[0512] It is preferable to add a dry gas stream to the stirred container. "Dry gas stream" means a gas or gas mixture with a relative humidity below the dew point at a temperature set in the stirred container. It is preferable to preheat the gas to a temperature in the range of 50°C to 300°C, for example, 80°C to 250°C, and particularly preferably in the range of 100°C to 200°C.

[0513] Preferably, for every 1 kg of silica suspension used, the solution is prepared at a rate of 10 m³ / h. 3 Up to 150m 3 Gas, for example, 20m per hour 3Up to 100m 3 Gas, preferably 30m³ / h 3 up to 70m 3 The gas is fed into the agitated container.

[0514] While agitated, a gas stream dries the silica suspension to form fine silica particles. The resulting particles are then removed from the stirring chamber.

[0515] The extracted particles are preferably further dried. The particles are preferably dried continuously, for example, in a rotary oven. The preferred drying temperature is in the range of 80°C to 250°C, for example, in the range of 100°C to 200°C, and particularly preferably in the range of 120°C to 180°C.

[0516] In the context of this invention, "continuous" means a process that can be operated continuously. This means that the substances and materials involved in the process can be added and removed during operation. The process does not need to be interrupted.

[0517] As an attribute of an item, such as a "continuous furnace," "continuous" means that the process or technological steps in which it operates can be carried out continuously.

[0518] The granules obtained by roller granulation can be filtered before or after drying. Filtration is preferred before drying. The filtered fine particles preferably have a particle size of less than 50 μm, for example, less than 80 μm, and particularly preferably less than 100 μm. The filtered fine particles also have a particle size greater than 900 μm, for example, greater than 700 μm, and particularly preferably greater than 500 μm. Larger particles can, in principle, be filtered out by any and all methods known to those skilled in the art and suitable for this purpose. Filtration of larger particles by a vibrating trough is preferred.

[0519] In another embodiment, roller pelleting is characterized by at least one, for example two or three, and particularly preferably all of the following features:

[0520] [a] Granulation is carried out in a rotating agitated container;

[0521] [b] Granulation is carried out under a gas flow of 10 kg to 150 kg of gas per hour per 1 kg of silica suspension;

[0522] [c] The input gas temperature is 40°C to 200°C;

[0523] [d] Filter out fine particles with a particle size of less than 100 μm and greater than 500 μm;

[0524] [e] The resulting fine particles have 15% to 30% residual moisture by weight;

[0525] [f] The fine particles formed are dried at 80°C to 250°C, preferably in a continuous drying tube, particularly to a residual moisture content of less than 1% by weight.

[0526] Silica particles obtained by granulation, particularly by spray or roller granulation, are further pretreated before being processed into quartz glass. This pretreatment can be used for various purposes, such as facilitating processing into quartz glass or influencing the characteristics of the resulting quartz glass. For example, the silica particles can be compressed, cleaned, surface modified, or dried.

[0527] In the following text, silica particles obtained by granulation but not and / or not yet further pretreated are referred to as "silica particles I". In the following text, silica particles prepared according to one or more pretreatment steps prior to the formation of a glass melt are referred to as "silica II".

[0528] The silica particles obtained by granulation, namely silica particles I, may have at least one of the following characteristics, preferably more than one:

[0529] [A] at 20m 2 / g to 50m 2 Within the range of / g, for example, in 20m 2 / g to 40m 2 Within the range of / g, it is particularly preferred to be within 25m 2 / g to 35m 2 BET surface area in the range of / g; in this case, the microporous component is preferably in the range of 4m 2 / g to 5m 2 Within the range of / g; for example, at 4.1m 2 / g to 4.9m 2 Within the range of / g; particularly preferred at 4.2m 2 / g to 4.8m 2 Operations on the BET surface area within the range of / g; and

[0530] [B] The average particle size is in the range of 180 μm to 300 μm, for example, in the range of 220 μm to 280 μm, and particularly preferably in the range of 230 μm to 270 μm;

[0531] [C] at 0.5 g / cm 3 Up to 1.2 g / cm 3 Within a range, for example, at 0.6 g / cm³ 3 Up to 1.1 g / cm 3 Within the range, especially at 0.7 g / cm 3 Up to 1.0 g / cm 3 Bulk density within the range;

[0532] [D] Carbon content less than 50 ppm, for example less than 40 ppm, or less than 30 ppm, or less than 20 ppm, or less than 10 ppm, particularly preferably in the range of 1 ppb to 5 ppm;

[0533] [E] Aluminum content less than 200 ppb, preferably less than 100 ppb, for example less than 50 ppb, or 1 ppb to 200 ppb, or 15 ppb to 100 ppb, particularly preferably in the range of 1 ppb to 50 ppb;

[0534] [F] at 0.5 g / cm 3 Up to 1.2 g / cm 3 Within a range, for example, at 0.6 g / cm³ 3 Up to 1.1 g / cm 3 Within the range, it is particularly preferred to be 0.75 g / cm³. 3 Up to 1.0 g / cm 3 Filling density within the range;

[0535] [G] Pore volume in the range of 0.1 mL / g to 1.5 mL / g, for example, in the range of 0.15 mL / g to 1.1 mL / g, and particularly preferably in the range of 0.2 mL / g to 0.8 mL / g.

[0536] [H] less than 200 ppm, preferably less than 150 ppm, for example less than 100 ppm, or less than 50 ppm, or less than 1 ppm, or less than 500 ppb, or less than 200 ppb, or chlorine content in the range of 1 ppb to less than 200 ppm, or 1 ppb to 100 ppm, or 1 ppb to 1 ppm, or 10 ppb to 500 ppb, or 10 ppb to 200 ppb, particularly preferably chlorine content in the range of 1 ppb to 80 ppb;

[0537] [I] The metal content of metals other than aluminum is less than 1000 ppb, preferably in the range of 1 ppb to 900 ppb, for example in the range of 1 ppb to 700 ppb, and particularly preferably in the range of 1 ppb to 500 ppb.

[0538] [J] Less than 10% by weight, preferably from 0.01% to 5% by weight, for example from 0.02% to 1% by weight, particularly preferably from 0.03% to 0.5% by weight;

[0539] The weight percentages (%), ppm, and ppb are based on the total weight of silica particles 1 in each case.

[0540] OH content, or hydroxyl group content, refers to the amount of OH groups in a material (e.g., silica powder, silica particles, or quartz glass). OH group content is determined spectroscopically in the infrared spectrum by comparing the first and third OH bands.

[0541] Chlorine content refers to the elemental chlorine or chloride ion content of silica particles, silica powder, or quartz glass.

[0542] The term "aluminum content" refers to the elemental aluminum or aluminum ion content of silica particles, silica powder, or quartz glass.

[0543] Silica particles I preferably have a size of 4m 2 / g to 5m 2 Within the range of / g, for example, at 4.1m 2 / g to 4.9m 2 Within the range of / g, it is particularly preferred to be within 4.2m. 2 / g to 4.8m 2 Micropore content within the range of / g.

[0544] Silica particles I preferably have a content of 2.1 g / cm³. 3 Up to 2.3 g / cm 3 Within the range, it is particularly preferred to be 2.18 g / cm³. 3 Up to 2.22 g / cm 3 Density within the range.

[0545] Particle size refers to the size of particles composed of primary particles in silica powder, slurry, or silica granules.

[0546] Average particle size refers to the arithmetic mean of all particle sizes of the material. D 50 The value indicates that, based on the total number of particles, 50% of the particles are smaller than the stated value. D 10 The value indicates that, based on the total number of particles, 10% of the particles are smaller than this value. D 90 The value indicates that 90% of the particles are smaller than the stated value, based on the total number of particles. Particle size is determined by dynamic image analysis according to ISO 13322-2:2006-11.

[0547] The silica particles I preferably have a particle size D in the range of 150 μm to 300 μm, for example, in the range of 180 μm to 280 μm, and particularly preferably in the range of 220 μm to 270 μm. 50 The silica particles preferably have a particle size D in the range of 50 μm to 150 μm, for example, in the range of 80 μm to 150 μm, and particularly preferably in the range of 100 μm to 150 μm. 10The silica particles preferably have a particle size D in the range of 250 μm to 620 μm, for example, in the range of 280 μm to 550 μm, and particularly preferably in the range of 300 μm to 450 μm. 90 .

[0548] The silica particles I preferably have the characteristic combination [A] / [B] / [C] or [A] / [B] / [E] or [A] / [B] / [G], further preferably the characteristic combination [A] / [B] / [C] / [E] or [A] / [B] / [C] / [G] or [A] / [B] / [E] / [G], and particularly preferably the characteristic combination [A] / [B] / [C] / [E] / [G].

[0549] Silica particles I preferably have the characteristic combination [A] / [B] / [C], wherein the BET surface area is 20m². 2 / g to 40m 2 The average particle size is in the range of 180 μm to 300 μm and the bulk density is in the range of 0.6 g / ml to 1.1 g / ml.

[0550] Silica particles I preferably have the characteristic combination [A] / [B] / [E], wherein the BET surface area is 20m². 2 / g to 40m 2 The average particle size is in the range of 180μm to 300μm and the aluminum content is in the range of 1ppb to 50ppb.

[0551] Silica particles I preferably have the characteristic combination [A] / [B] / [G], wherein the BET surface area is 20m². 2 / g to 40m 2 The average particle size is in the range of 180 μm to 300 μm and the pore volume is in the range of 0.2 ml / g to 0.8 ml / g.

[0552] Silica particles I preferably have the characteristic combination [A] / [B] / [C] / [E], wherein the BET surface area is 20m². 2 / g to 40m 2 The average size is in the range of 180 μm to 300 μm, the bulk density is in the range of 0.6 g / ml to 1.1 g / ml, and the aluminum content is in the range of 1 ppb to 50 ppb.

[0553] Silica particles I preferably have the characteristic combination [A] / [B] / [C] / [G], wherein the BET surface area is 20m². 2 / g to 40m 2The average particle size is in the range of 180 μm to 300 μm, the bulk density is in the range of 0.6 g / ml to 1.1 g / ml, and the pore volume is in the range of 0.2 ml / g to 0.8 ml / g.

[0554] Silica particles I preferably have the characteristic combination [A] / [B] / [E] / [G], wherein the BET surface area is 20m². 2 / g to 40m 2 The average particle size is in the range of 180 μm to 300 μm, the aluminum content is in the range of 1 ppb to 50 ppb, and the pore volume is in the range of 0.2 ml / g to 0.8 ml / g.

[0555] Silica particles I preferably have the characteristic combination [A] / [B] / [C] / [E] / [G], wherein the BET surface area is 20m². 2 / g to 40m 2 The average particle size is in the range of 180 μm to 300 μm, the bulk density is in the range of 0.6 g / ml to 1.1 g / ml, the aluminum content is in the range of 1 ppb to 50 ppb, and the pore volume is in the range of 0.2 ml / g to 0.8 ml / g.

[0556] Optional particle treatment

[0557] Silica particles I can be obtained by heat treatment, mechanical treatment, or chemical treatment, or a combination of two or more treatments.

[0558] a.Chemistry

[0559] According to a preferred embodiment of the first objective of the present invention, silica particles I have a carbon content w C(1) Carbon content w C(1) Preferably less than 50 ppm, for example in the range of less than 40 ppm or less than 30 ppm, particularly preferably in the range of 1 ppb to 20 ppm, in each case based on the total weight of silica particles.

[0560] According to a preferred embodiment of the invention's first objective, the silica particles comprise at least two particles. These at least two particles are preferably movable relative to each other. This relative movement can, in principle, be induced by any and all suitable means known to a person skilled in the art. Mixing is particularly preferred. Mixing can, in principle, be carried out in any desired manner, preferably using a continuous furnace. Correspondingly, the at least two particles are preferably movable relative to each other by movement within a continuous furnace (e.g., a rotary furnace).

[0561] A continuous furnace refers to a furnace in which loading and unloading (“charging”) occurs continuously. Examples of continuous furnaces are rotary furnaces, roller furnaces, conveyor furnaces, and pusher furnaces. Silica particles I are preferably processed using a rotary furnace.

[0562] According to a preferred embodiment of the invention with a first objective, silica particles are treated with a reagent to obtain silica II. The treatment is performed to alter the concentration of certain substances in the silica particles. Silica particles I may have contaminants or certain functional groups, such as OH groups, carbides, transition metals, alkali metals, and alkaline earth metals, in proportions that should be reduced. The contaminants and functional groups may originate from the input material or the process. Silica particles I can be used for various purposes: for example, using treated silica particles I, i.e., silica particles II, can simplify the processing of silica particles into quartz glass. This option can also be used to adjust the characteristics of the resulting quartz glass. For example, silica particles I can be cleaned or surface modified. That is, silica particles I can be used to improve the characteristics of the resulting quartz glass.

[0563] Reagents such as gases or combinations of more than one gas are preferred. These are also referred to as gas mixtures. In principle, any and all gases known to a person skilled in the art can be used, which are known and appear to be suitable for the process. Preferably, the gas is selected from the group consisting of: HCl, Cl2, F2, O2, O3, H2, C2F4, C2F6, HClO4, air, inert gases (e.g., N2, He, Ne, Ar, Kr), or combinations of two or more of these. The process is preferably carried out in the presence of one gas or a combination of two or more gases, preferably in a countercurrent or parallel gas flow.

[0564] The reagent is preferably selected from the group consisting of HCl, Cl2, F2, O2, O3, or combinations of two or more thereof. Mixtures of two or more of the above gases are preferred for treating silica particles.

[0565] The presence of I. F, Cl, or both can remove metals, such as transition metals, alkali metals, and alkaline earth metals, that act as contaminants from silica particles I. Here, these metals can be combined with components of the gas mixture under process conditions to obtain gaseous components, which are then removed from the particles and thus no longer present in the particles. More preferably, the OH content of silica particles I can be reduced by treating silica particles I with these gases.

[0566] A mixture of HCl and Cl2 gases is preferably used as a reagent. Preferably, the gas mixture has an HCl content in the range of 1 vol% to 30 vol%, for example, in the range of 2 vol% to 15 vol%, and particularly preferably in the range of 3 vol% to 10 vol%. Also preferably, the gas mixture has a Cl2 content in the range of 20 vol% to 70 vol%, for example, in the range of 25 vol% to 65 vol%, and particularly preferably in the range of 30 vol% to 60 vol%. The remaining 100 vol% may consist of one or more inert gases (e.g., N2, He, Ne, Ar, Kr) or air. The inert gas component of the reagent is preferably in the range of 0 vol% to less than 50 vol%, for example, in the range of 1 vol% to 40 vol% or 5 vol% to 30 vol%, and particularly preferably in the range of 10 vol% to 20 vol%, in each case based on the total volume of the reagent.

[0567] O2, C2F2, or a mixture thereof with Cl2 are preferred for purifying silica particles I made from siloxanes or mixtures of more than one siloxane.

[0568] The reagent, in the form of a gas or gas mixture, preferably contacts the silica particles with a gas stream or a portion of the gas stream in the flow rate range of 50 l / h to 2000 l / h, for example, in the range of 100 l / h to 1000 l / h, and particularly preferably in the range of 200 l / h to 500 l / h. A preferred design for the contact is that the gas stream and the silica particles are in contact in a continuous furnace, such as a rotary tube furnace. Another preferred form of contact is a fluidized bed process.

[0569] Treating silica particles I with a reagent yields particles with a carbon content w. C(2) Silica particles II. The carbon content w of silica particles II. C(2) The carbon content of particles smaller than silica particles III is less than that of silica particles I. C(1) In each case, the weight is based on the total weight of the silica particles involved. Preferably, w C(2) Compared to w C(1) The content ranges from 0.5% to 99%, for example, from 20% to 80% or 50% to 95%, with 60% to 99% being particularly preferred.

[0570] b. heat

[0571] Prior to forming the glass melt, it is preferable to subject the silica particles to heat treatment, mechanical treatment, or a combination of these treatments. One or more of these additional treatments may be used before or during reagent treatment. Alternatively or additionally, silica particles II may also be subjected to additional treatment. The common name “silica particles” used below includes alternatives “silica particles I” and “silica particles II”. The treatments described below may also be performed on “silica particles I” and the treated silica particles I (“silica particles II”). Such heat treatment is preferably used after one of the above-described chemical treatments.

[0572] Treating silica particles can be used for a variety of purposes. For example, the treatment makes the silica particles easier to process into quartz glass. The treatment can also affect the characteristics of the resulting quartz glass. For example, the silica particles can be compressed, cleaned, surface modified, or dried, which can reduce the specific surface area (BET). Agglomerating the silica particles can also increase their packing density and average particle size. Heat treatment can be dynamic or static.

[0573] In principle, any and all furnaces suitable for dynamic heat treatment are those that heat-treat silica particles and allow the silica particles to move during the process. Continuous furnaces are preferred for dynamic heat treatment.

[0574] The preferred average residence time of silica particles in dynamic heat treatment depends on the quantity. In the case of dynamic heat treatment, the average residence time of silica particles is preferably in the range of 10 min to 180 min, for example, in the range of 20 min to 120 min or 30 min to 90 min. Particularly preferred is that when silica particles are subjected to thermodynamic treatment, they have an average residence time in the range of 30 min to 90 min.

[0575] In the case of a continuous process, the residence time is the quantity of silica particles loaded into a defined portion, such as g, kg, or t. The residence time begins and ends when the particles are fed into the continuous furnace operation and when they leave the continuous furnace operation, respectively.

[0576] In continuous thermodynamic heat treatment processes, the throughput of silica particles is preferably in the range of 1 kg / h to 50 kg / h, for example, in the range of 5 kg / h to 40 kg / h or 8 kg / h to 30 kg / h. Particularly preferred is the throughput in the range of 10 kg / h to 20 kg / h.

[0577] In the case of discontinuous thermodynamic processing, the processing time is the time between loading and unloading the furnace.

[0578] In the case of discontinuous dynamic heat treatment processes, the throughput is in the range of 1 kg / h to 50 kg / h, for example, in the range of 5 kg / h to 40 kg / h or 8 kg / h to 30 kg / h. Particularly preferred is the throughput in the range of 10 kg / h to 20 kg / h. The throughput can be achieved by processing a given amount of load for one hour. According to another embodiment, the throughput can be achieved by multiple batches per hour, wherein, for example, the number of a batch is equal to the hourly throughput [divided] by the number of batches. The processing time is then equal to the hour fraction obtained by dividing 60 minutes by the number of batches per hour.

[0579] The silica particles are preferably subjected to dynamic heat treatment at a furnace temperature of at least 500°C, for example, in the range of 510°C to 1700°C, 550°C to 1500°C, or 580°C to 1300°C, and particularly preferably in the range of 600°C to 1200°C.

[0580] Typically, the furnace is located at a specified temperature within the furnace chamber. Based on the total processing time and total furnace length, this temperature preferably varies by less than ±10% compared to the specified temperature, regardless of the processing time or location within the furnace.

[0581] Alternatively, a continuous process for dynamically heat-treating silica particles, particularly at different furnace temperatures. For example, the furnace may be at a constant temperature during the treatment time, with the temperature varying in segments along the length of the furnace. Such segments may be of the same length or different lengths. Preferably, in this case, the temperature increases from the furnace inlet to the furnace outlet. The temperature at the inlet is preferably at least 100°C lower than that at the outlet, for example, 150°C, 200°C, 300°C, or 400°C lower. Furthermore, the temperature at the outlet is preferably at least 500°C, for example, in the range of 510°C to 1700°C, 550°C to 1500°C, or 580°C to 1300°C, particularly preferably in the range of 600°C to 1200°C; and the temperature at the inlet is preferably at least 300°C, for example, 400°C to 1000°C, 450°C to 900°C, 500°C to 800°C, or 550°C to 750°C, particularly preferably 600°C to 700°C. Any temperature range specified at the furnace inlet can also be combined with any temperature range at the furnace outlet. Preferred combinations of furnace inlet and furnace outlet temperature ranges are as follows:

[0582] Furnace inlet temperature range [°C] Furnace outlet temperature range [°C] 400-1000 510-1300 450-900 550-1260 480-850 580-1200 500-800 600-1100 530-750 630-1050

[0583] The static heat treatment of silica particles is preferably carried out in a crucible arranged in a furnace. Suitable crucibles are sintered crucibles or sheet metal crucibles. Roller-type sheet metal crucibles made of multiple riveted plates are preferred. The crucible material is, for example, a refractory metal, particularly tungsten, molybdenum, and tantalum. The crucible can also be formed from graphite, or, in the case of a refractory metal furnace, hammered from graphite foil. Preferably, the crucible can also be made of silica. Silica crucibles are particularly preferred.

[0584] The average residence time of silica particles during static heat treatment depends on the quantity. When static heat treatment is performed with 20 kg of silica particles I, the average residence time of the silica particles is preferably in the range of 10 min to 180 min, for example, in the range of 20 min to 120 min, and particularly preferably in the range of 30 min to 90 min.

[0585] The silica particles are preferably processed at a furnace temperature of at least 800°C, for example, in the range of 900°C to 1700°C, 950°C to 1600°C, 1000°C to 1500°C, or 1050°C to 1400°C, and particularly preferably in the range of 1100°C to 1300°C.

[0586] The silica particles I undergoing static heat treatment are preferably treated at a constant furnace temperature. Static heat treatment can also be performed at a variable furnace temperature, in which case the temperature preferably decreases during the treatment process, wherein the temperature at the beginning of the treatment is at least 50°C lower than the temperature at the end, for example, 70°C, 80°C, 100°C, or 110°C lower, and wherein the temperature at the end is preferably at least 800°C, for example in the range of 900°C to 1700°C, 950°C to 1600°C, 1000°C to 1500°C, or 1050°C to 1400°C, particularly preferably in the range of 1100°C to 1300°C.

[0587] c. Machinery

[0588] According to another preferred embodiment, the silica particles are mechanically treated prior to the formation of the glass melt. Mechanical treatment of the silica particles increases their bulk density. This mechanical treatment can be performed after heat treatment as described above. Mechanical treatment avoids agglomerates within the silica particles, and thus prevents the average particle size of individual silica particles from becoming excessively large. Excessively large agglomerates may make further processing more difficult, or have an adverse effect on the characteristics of the quartz glass prepared by the method of the present invention, or a combination of both. Mechanical treatment of the silica particles also promotes uniform contact between the surface of individual silica particles and one or more gases. Specifically, this is achieved through a combination of simultaneous mechanical treatment and chemical treatment with one or more gases, thereby improving the effectiveness of the chemical treatment.

[0589] Silica granulation can be carried out, for example, by rotating the tube of a rotary tube furnace, causing two or more silica particles to move relative to each other.

[0590] Silica particles I are preferably subjected to chemical, thermal, and mechanical treatments. These treatments can be performed simultaneously, sequentially, or overlapping. Overlapping means that one treatment is not completed before the next treatment begins. The criterion for evaluating the timing sequence is the work done on the silica particles during loading, rather than, for example, the operation time of a single process as a whole. This is particularly true for the simultaneous chemical, thermal, and mechanical treatment of silica particles I.

[0591] Chemical treatment reduces the contaminant content in silica particles I. To this end, silica particles I can be treated in a rotary tube furnace at elevated temperatures under a chlorine and oxygen atmosphere. This evaporates water from the silica particles I, and organic materials react to form CO and CO2. Metallic contaminants can be converted into volatile chlorine compounds.

[0592] Silica particles I are preferably processed in a rotary furnace in a chlorine and oxygen atmosphere at a temperature of at least 500°C, preferably in the temperature range of 550°C to 1300°C, 600°C to 1260°C, 650°C to 1200°C, or 700°C to 1000°C, and particularly preferably in the temperature range of 700°C to 900°C. The chlorine-containing atmosphere includes, for example, HCl or Cl2, or a combination of both. This treatment reduces the carbon content.

[0593] It is also preferable to reduce alkali and iron contamination; and it is also preferable to reduce the number of OH groups. Temperatures below 700°C may prolong the processing time, while temperatures above 1100°C may cause particle pore closure and trap chlorine or gaseous chlorine compounds.

[0594] d. Combined processing

[0595] Preferably, more than one chemical treatment step may be performed consecutively, along with heat treatment and mechanical treatment. For example, the silica particles may be treated first in a chlorine atmosphere and then in an oxygen atmosphere. The resulting low concentrations of carbon, hydroxyl groups, and chlorine facilitate the melting of the particles.

[0596] According to another preferred embodiment, the pretreatment of silica particles prior to the formation of the glass melt is characterized by at least one, at least two, or at least three of the following features, with a particularly preferred combination of all of the following features:

[0597] N1) The reagent contains HCl, Cl2, or a combination thereof;

[0598] N2 treatment is carried out in a rotary furnace;

[0599] The N3 treatment is carried out at a temperature range of 600°C to 900°C.

[0600] N4) The reagent forms a countercurrent;

[0601] The N5 reagent has a gas flow rate of 50 l / h to 2000 l / h, preferably 100 l / h to 1000 l / h, and particularly preferably 200 l / h to 500 l / h;

[0602] N6) reagents contain inert gases ranging from 0% to less than 50% by volume.

[0603] The silica particles thus obtained are also called silica particles II, as described above. Particularly preferably, silica particles II are obtained from silica particles I in a rotary furnace by means of a combination of heat treatment, mechanical treatment and chemical treatment.

[0604] Silica particles II may have one or more of the following characteristics:

[0605] (A) at 10m 2 / g to 35m 2 Within the range of / g, for example, in 10m 2 / g to 30m 2 Within the range of / g, it is particularly preferred to be within 20m 2 / g to 30m 2 BET surface area within the range of / g, and

[0606] (B) Average particle size in the range of 100 μm to 300 μm, for example in the range of 150 μm to 280 μm or 200 μm to 270 μm, particularly preferably in the range of 230 μm to 260 μm.

[0607] (C) at 0.7 g / cm 3 Up to 1.2 g / cm3 Within a range, for example, at 0.75 g / cm³ 3 Up to 1.1 g / cm 3 Within the range, it is particularly preferred to be within 0.8 g / cm³. 3 Up to 1.0 g / cm 3 Bulk density within the range;

[0608] (D) Carbon content less than 5 ppm, for example less than 4.5 ppm or in the range of 1 ppb to 4 ppm, with a particular preference for less than 4 ppm;

[0609] (E) Aluminum content less than 200 ppb, for example less than 150 ppb or less than 100 ppb or 1 ppb to 150 ppb or 1 ppb to 100 ppb, particularly preferably in the range of 1 ppb to 80 ppb;

[0610] (F) at 0.7 g / cm 3 Up to 1.2 g / cm 3 Within a range, for example, at 0.75 g / cm³ 3 Up to 1.1 g / cm 3 Within the range, it is particularly preferred to be within 0.8 g / cm³. 3 Up to 1.0 g / cm 3 Filling density within the range;

[0611] (G) Pore volume in the range of 0.1 ml / g to 2.5 ml / g, for example in the range of 0.2 ml / g to 1.5 ml / g, and particularly preferably in the range of 0.4 ml / g to 1 ml / g;

[0612] (H) less than 500 ppm, preferably less than 400 ppm, for example less than 350 ppm or preferably less than 330 ppm or chlorine content in the range of 1 ppb to 500 ppm or 10 ppb to 450 ppm, particularly preferably 50 ppb to 300 ppm;

[0613] (I) The metal content of metals other than aluminum is less than 1000 ppb, for example, in the range of 1 ppb to 400 ppb, and particularly preferably in the range of 1 ppb to 200 ppb.

[0614] (J) The residual moisture content is less than 3% by weight, for example, from 0.001% by weight to 2% by weight, and particularly preferably from 0.01% by weight to 1% by weight.

[0615] The weight percentages, ppm, and ppb are based on the total weight of silica particles II in each case.

[0616] Silica particles II preferably have a particle size of 1m 2 / g to 2m 2Within the range of / g, for example, in 1.2m 2 / g to 1.9m 2 Within the range of / g, it is particularly preferred to be within 1.3m. 2 / g to 1.8m 2 Micropore content within the range of / g.

[0617] Silica particles II preferably have a density of 0.5 g / cm³. 3 Up to 2.0 g / cm 3 For example, 0.6 g / cm³ 3 Up to 1.5g / cm 3 0.8g / cm³ is a preferred grade. 3 Up to 1.2 g / cm 3 Density within the specified range. Density is determined by the method described in the test method.

[0618] The silica particles II preferably have a particle size D in the range of 150 μm to 250 μm, for example, in the range of 180 μm to 250 μm, and particularly preferably in the range of 200 μm to 250 μm. 50 The silica particles II are particularly preferably having a particle size D in the range of 50 μm to 150 μm, for example, in the range of 80 μm to 150 μm, and particularly preferably in the range of 100 μm to 150 μm. 10 More preferably, the silica particles II have a particle size D in the range of 250 μm to 450 μm, for example in the range of 280 μm to 420 μm, particularly in the range of 300 μm to 400 μm. 90 .

[0619] The silica particles II preferably have the characteristic combination (A) / (B) / (D) or (A) / (B) / (F) or (A) / (B) / (I), further preferably the characteristic combination (A) / (B) / (D) / (F) or (A) / (B) / (D) / (I) or (A) / (B) / (F) / (I), and particularly preferably the characteristic combination (A) / (B) / (D) / (F) / (I).

[0620] Silica particles II preferably have the characteristic combination (A) / (B) / (D), wherein the BET surface area is 10 m². 2 / g to 30m 2 The average particle size is in the range of 150 μm to 280 μm and the carbon content is less than 4 ppm.

[0621] Silica particles II preferably have the characteristic combination (A) / (B) / (F), wherein the BET surface area is 10 m². 2 / g to 30m 2The average particle size is in the range of 150 μm to 280 μm and the packing density is in the range of 0.8 g / ml to 1.0 g / ml.

[0622] Silica particles II preferably have the characteristic combination (A) / (B) / (I), wherein the BET surface area is 10 m². 2 / g to 30m 2 The average particle size is in the range of 150 μm to 280 μm and the metal content of metals other than aluminum is in the range of 1 ppb to 400 ppb.

[0623] Silica particles II preferably have the characteristic combination (A) / (B) / (D) / (F), wherein the BET surface area is 10 m². 2 / g to 30m 2 The average particle size is in the range of 150 μm to 280 μm, the carbon content is less than 4 ppm, and the packing density is in the range of 0.8 g / ml to 1.0 g / ml.

[0624] Silica particles II preferably have the characteristic combination (A) / (B) / (D) / (I), wherein the BET surface area is 10m². 2 / g to 30m 2 Within the range of / g, the average particle size is in the range of 150μm to 280μm, the carbon content is less than 4ppm and the metal content of metals other than aluminum is in the range of 1ppb to 400ppb.

[0625] Silica particles II preferably have the characteristic combination (A) / (B) / (F) / (I), wherein the BET surface area is 10m². 2 / g to 30m 2 The average particle size is in the range of 150 μm to 280 μm, the packing density is in the range of 0.8 g / ml to 1.0 g / ml, and the metal content (excluding aluminum) is in the range of 1 ppb to 400 ppb.

[0626] Silica particles II preferably have the characteristic combination (A) / (B) / (D) / (F) / (I), wherein the BET surface area is 10m². 2 / g to 30m 2 The particles are in the range of / g, with an average particle size in the range of 150μm to 280μm, a carbon content of less than 4ppm, a packing density in the range of 0.8g / ml to 1.0g / ml, and a metal content other than aluminum in the range of 1ppb to 400ppb.

[0627] Silica particles (silica particle I and / or silica particle II or both) may contain other components, for example, in the form of molecules, ions or elements. Based on the total weight of the silica particles, the silica particles preferably contain less than 5 ppm, for example less than 3 ppm, particularly preferably less than 1 ppm of atoms other than Si, O, H, C, and Cl, and preferably the amount of atoms other than Si, O, H, C, and Cl is at least 1 ppb. Other components may be particularly selected from the group consisting of: carbon, fluorides, iodides, bromides, phosphorus or mixtures of at least two of them.

[0628] In each case, based on the total weight of silica, the silica particles preferably contain less than 10 ppm of carbon, for example less than 8 ppm or less than 5 ppm, and particularly preferably less than 4 ppm of carbon. Silica particles typically contain at least 1 ppb of carbon.

[0629] In each case, based on the total weight of other components in the silica particles, the silica particles preferably contain less than 100 ppm, for example less than 80 ppm, and particularly preferably less than 70 ppm of other components, although they typically contain at least 1 ppb of other components.

[0630] Pretreatment steps before smelting

[0631] The silica particles formed in step v.) may undergo one or more pretreatment steps before being heated in step vi.) to obtain the glass melt. These pretreatment steps can be conceived as, for example, heat treatment or mechanical processing.

[0632] a.) Precompression

[0633] Silica particles can be compressed, for example, during step vi., prior to heating. The term "compression" means reducing the BET surface area and pore volume.

[0634] Silica particles are preferably heat-treated by heating, or mechanically treated by applying pressure (e.g., rolling or pressing). Silica particles are preferably compressed by heating. Particularly preferred is the compression of the silica particles by heating via a preheating section connected to a melting furnace.

[0635] Silica is preferably compressed by heating at a temperature in the range of 800°C to 1400°C, for example, at a temperature in the range of 850°C to 1300°C, and particularly preferably at a temperature in the range of 900°C to 1200°C.

[0636] In another embodiment, the BET surface area of ​​the silica particles does not decrease to less than 5 m² before step vi.).2 / g, preferably not reduced to less than 7m 2 / g or not reduced to less than 10m 2 / g, preferably not reduced to less than 15m 2 / g. It is also preferred that the BET surface area of ​​the silica particles is not reduced before step vi.) compared with the silica particles provided in step i.).

[0637] In another embodiment, the BET surface area of ​​the silica particles is reduced to less than 20 m². 2 / g, for example, reduced to less than 15m 2 / g, or reduced to less than 10m 2 / g, or reduced to greater than 5m 2 / g to less than 20m 2 / g or 7m 2 / g to 15m 2 The range of / g is particularly preferably reduced to 9m. 2 / g to 12m 2 The range is / g. Compared to the silica particles formed in step v.), the BET surface area of ​​the silica particles before step vi.) is preferably reduced by less than 40m². 2 / g, for example, decrease by 1m 2 / g to 20m 2 / g or 2m 2 / g to 10m 2 / g, with a particularly preferred reduction of 3m 2 / g to 8m 2 / g, where the BET surface area is greater than 5m² after compression. 2 / g.

[0638] The compressed silica particles preferably have at least one, for example at least two, at least three, or at least four, and particularly preferably at least five of the following characteristics:

[0639] A. In areas greater than 5m 2 / g to less than 35m 2 Within the range of / g, for example, 10m 2 / g to 30m 2 / g, especially preferred at 15m 2 / g to 25m 2 BET surface area within the range of / g;

[0640] B. Particle size D is particularly preferred in the range of 120 μm to 200 μm, within the range of 100 μm to 300 μm. 10 ;

[0641] C. Particle size D is particularly preferred in the range of 200 μm to 350 μm, within the range of 150 μm to 550 μm. 50 ;

[0642] D. Particle size in the range of 300 μm to 650 μm, particularly preferably in the range of 400 μm to 500 μm. 90 ;

[0643] E. Between 0.7 g / cm and 1.6 g / cm, or 0.8 g / cm 3 Up to 1.2 g / cm 3 1.0g / cm³ is particularly preferred. 3 Up to 1.4 g / cm 3 Bulk density within the range;

[0644] F. at 1.0 g / cm 3 Up to 1.4 g / cm 3 A particularly preferred concentration is 1.15 g / cm³. 3 Up to 1.35 g / cm 3 Filling density within the range;

[0645] G. Carbon content less than 5 ppm, for example less than 4.5 ppm, and particularly preferred to be less than 4 ppm;

[0646] H. Chlorine content less than 500 ppm, with a particularly preferred chlorine content of 1 ppb to 200 ppm.

[0647] The ppm and ppb values ​​in each case are based on the total weight of the compressed silica particles.

[0648] The compressed silica particles preferably have the characteristic combination A. / F. / G. or A. / F. / H. or A. / G. / H., and the characteristic combination A. / F. / G. / H. is particularly preferred.

[0649] The compressed silica particles preferably have the characteristic combination A. / F. / G., wherein the BET surface area is 10 m². 2 / g to 30m 2 Within the range of / g, the packing density is in the range of 1.15g / ml to 1.35g / ml and the carbon content is less than 4ppm.

[0650] The compressed silica particles preferably have a characteristic combination of A. / F. / H., wherein the BET surface area is 10 m². 2 / g to 30m 2 The packing density is in the range of 1.15 g / ml to 1.35 g / ml and the chlorine content is in the range of 1 ppb to 200 ppm.

[0651] The compressed silica particles preferably have a characteristic combination of A. / G. / H., wherein the BET surface area is 10 m². 2 / g to 30m 2 Within the range of / g, the carbon content is less than 4ppm and the chlorine content is in the range of 1ppb to 200ppm.

[0652] The compressed silica particles preferably have a characteristic combination of A. / F. / G. / H., wherein the BET surface area is 10 m². 2 / g to 30m 2 Within the range of / g, the packing density is in the range of 1.15g / ml to 1.35g / ml, the carbon content is less than 4ppm and the carbon content is in the range of 1ppb to 200ppm.

[0653] b.) Adding silicon compounds

[0654] A silicon component other than silicon dioxide may be added in at least one step of the process for manufacturing quartz glass. Hereinafter, the addition of a silicon component other than silicon dioxide is also referred to as Si doping.

[0655] The silicon component other than silica can, in principle, be added in any desired form, such as a solid, liquid, gas, solution, or dispersion. The silicon component other than silica is preferably added in powder form. The powder or the silica component other than silica preferably has an average particle size of up to 10 mm, for example, up to 1000 μm, up to 400 μm, or in the range of 1 μm to 400 μm, for example, 2 μm to 200 μm, or 3 μm to 100 μm, particularly preferably in the range of 1 μm to 50 μm or 2 μm to 20 μm. The particle size data is based on the state of the silicon component other than silica at room temperature. In a preferred alternative embodiment, the silicon component other than silica can be added in liquid or gaseous form.

[0656] The silicon component other than silica is preferably added in an amount ranging from 1 ppm to 100,000 ppm, for example, from 10 ppm to 10,000 ppm or from 30 ppm to 1,000 ppm or from 50 ppm to 500 ppm, particularly preferably from 80 ppm to 200 ppm, and even more particularly preferably from 200 ppm to 300 ppm, in each case based on the total weight of silica.

[0657] The silicon component other than silicon dioxide preferably has a purity of at least 99.5% by weight, for example at least 99.8% by weight, or at least 99.9% by weight, or at least 99.99% by weight, particularly preferably at least 99.999% by weight, based on the total weight of the silicon component in each case.

[0658] The silicon component other than silicon dioxide preferably has a carbon content of no more than 10 ppm, for example no more than 50 ppm, and particularly preferably no more than 1 ppm, based on the total weight of the silicon component in each case.

[0659] The silicon component other than silicon dioxide is preferably selected from silicon, silicon-hydrides, silicon-oxygen compounds, or silicon-hydrogen-oxygen compounds. The silicon component other than silicon dioxide is preferably elemental silicon.

[0660] The silicon component, excluding silica, preferably has a contaminant amount of no more than 250 ppm, for example no more than 150 ppm, and particularly preferably no more than 100 ppm, selected from the group consisting of Al, Ca, Co, Cr, Cu, Fe, Ge, Hf, K, Li, Mg, Mn, Mo, Na, Nb, Ni, Ti, V, W, Zn, and Zr, based on the total weight of the silicon component in each case. This is particularly preferred if the selected silicon component is silicon.

[0661] In principle, Si doping can be performed at any step of the process. Silicon components other than silicon dioxide can already be added in process steps i.) or ii.). In another embodiment, silicon components other than silicon dioxide are added simultaneously with the processing of silicon dioxide powder into silicon dioxide particles (step v.). For example, silicon components other than silicon dioxide can be added to the silicon dioxide before, during, or after granulation. Furthermore, silicon components can be injected into the glass melt in step vi.); however, adding them during one or more of process steps i.), ii.), and v.) is preferred, as they are added in step vi. Specifically, they are added in step v.).

[0662] Preferably, silicon components other than silicon dioxide can be added to a slurry containing silicon dioxide powder to inject Si. For this purpose, for example, the silicon components other than silicon dioxide are mixed with silicon dioxide particle powder and then slurried in a liquid, or the silicon dioxide powder is injected into a slurry or solution of silicon components other than silicon dioxide and slurried.

[0663] Preferably, silicon can be injected by adding silicon components other than silica during granulation. In principle, silicon components other than silica can be added at any desired time during granulation. In the case of spray granulation, the silicon components other than silica can be injected into the spray tower along with the slurry via a nozzle. In the case of roller granulation, the silicon components other than silica can be injected, for example, in solid form or in slurry form after the slurry has been injected into a mixing vessel.

[0664] More preferably, silicon can be doped by adding silicon components other than silicon dioxide after granulation. The silicon dioxide particles can be doped during further processing, preferably by adding silicon components other than silicon dioxide during heat treatment or mechanical processing of the silicon dioxide, or during its pre-compression.

[0665] More preferably, silicon components other than silicon dioxide may also be added during more than one of the above-mentioned sections, particularly during and after heat treatment or mechanical treatment of the silicon dioxide particles or their pre-compression.

[0666] The silicon component other than silica can, in principle, be silicon or any silicon compound known to those skilled in the art to have reducing properties. The silicon component other than silica is preferably silicon, a silicon-hydrogen compound (such as silanes), a silicon-oxygen compound (such as silicon monoxide), or a silicon-hydrogen-oxygen compound (such as disiloxanes). Preferred examples of silanes are methanesilane, disilane, propane, butane, pentasilane, hexane, heptane, higher carbon homologues and isomers of those listed above, as well as cyclic silanes such as cyclopentane. Silicon is particularly preferred.

[0667] In another embodiment, the silicon component other than silicon dioxide can be added to the melting furnace together with the silicon dioxide particles. Silicon, as the silicon component other than silicon dioxide, is preferably injected into the melting furnace together with the silicon dioxide particles. Silicon is preferably added in powder form, particularly at the particle size already described regarding the addition of the silicon component other than silicon.

[0668] Silicon components other than silica are preferably added to the silica particles before they are injected into the melting furnace. In principle, they can be added at any time after particle formation, such as in the preheating section, before or simultaneously with the pre-compression of the silica particles.

[0669] Silica particles obtained by adding silicon components other than silicon dioxide are called "Si-doped particles". Si-doped particles preferably have at least one, for example at least two, three, or four of the following characteristics, and particularly preferably at least five:

[0670] [1] In greater than 5m 2 / g to less than 40m 2 Within the range of / g, for example, 10m 2 / g to 30m 2 / g, especially preferred at 15m 2 / g to 25m 2 BET surface area within the range of / g;

[0671] [2] Particle size D is particularly preferred in the range of 120 μm to 200 μm within the range of 100 μm to 300 μm. 10 ;

[0672] [3] Particle size D is particularly preferred in the range of 200 μm to 350 μm within the range of 150 μm to 550 μm. 50 ;

[0673] [4] Particle size D is particularly preferred in the range of 400 μm to 500 μm, within the range of 300 μm to 650 μm. 90 ;

[0674] [5] at 0.8 g / cm 3 Up to 1.6 g / cm 3 1.0g / cm³ is particularly preferred. 3 Up to 1.4 g / cm 3 Bulk density within the range;

[0675] [6] at 1.0 g / cm 3 Up to 1.4 g / cm 3 A particularly preferred concentration is 1.15 g / cm³. 3 Up to 1.35 g / cm 3 Filling density within the range;

[0676] [7] The carbon content is less than 5 ppm, for example less than 4.5 ppm, and particularly preferably less than 4 ppm;

[0677] [8] Chlorine content less than 500 ppm, particularly preferred to be 1 ppb to 200 ppm.

[0678] [9] The aluminum content is less than 200 ppb, and is particularly preferred to be between 1 ppb and 100 ppb;

[0679]

[10] The metal content of metals other than aluminum is less than 1000 ppb, for example in the range of 1 ppb to 400 ppb, and particularly preferably in the range of 1 ppb to 200 ppb.

[0680]

[11] Less than 3% by weight, for example, from 0.001% by weight to 2% by weight, particularly preferably from 0.01% by weight to 1% by weight;

[0681] The weight percentages, ppm, and ppb are based on the total weight of the Si injection particles in each case.

[0682] Step vi.)

[0683] A glass melt is formed from the silica particles in step vi.). This typically involves heating the silica particles until a glass melt is obtained. Heating the silica particles into a glass melt can, in principle, be done by any method known to a person skilled in the art for this purpose.

[0684] V-Zug for preparing glass melts

[0685] The formation of glass melt from silica particles (e.g., by heating) can be carried out through a continuous process, wherein it is preferable to continuously feed silica particles into or continuously remove glass melt from the furnace, or both. It is also preferable to continuously feed silica particles into the furnace and continuously remove gaseous melt from the furnace.

[0686] A suitable furnace is, in principle, a furnace having at least one inlet and at least one outlet. An inlet means an opening through which silica and other materials (if any) can be fed into the furnace. An outlet means an opening through which at least a portion of the silica can be removed from the furnace. For example, the furnace can be vertically or horizontally oriented. A furnace is preferably vertically oriented. At least one inlet is preferably above at least one outlet. Regarding the fittings and features of the furnace, particularly the inlet and outlet, "above" means that the fitting or feature arranged "above" another fitting or feature has a higher position above zero absolute height (NN). "Vertical" means that the direct connection between the inlet and outlet of the oven differs from the direction of gravity by no more than 30°.

[0687] According to one embodiment, the furnace includes a suspended sheet metal crucible into which silica particles are fed and heated to obtain a glass melt. A sheet metal crucible refers to a crucible comprising at least one rolled metal sheet. Preferably, the sheet metal crucible has more than one rolled metal sheet connected by suitable joints such as rivets. A suspended sheet metal crucible refers to a sheet metal crucible suspended in the furnace as described above.

[0688] Suspended sheet crucibles can, in principle, be made of any and all materials known to those skilled in the art suitable for molten silica. Preferably, the sheet comprises a sintered material, such as so-called sintered metal. "Sintered metal" means a metal or alloy obtained by sintering metal powder. Sintered metal can be converted into sheet, for example, by rolling. Sintered metal sheet crucibles preferably comprise two or more sheets. These sheets can be made from rolled sintered metal.

[0689] The metal sheet in the metal sheet crucible preferably contains at least one element selected from the group consisting of refractory metals. "Refractory metals" means metals from subgroups 4 (Ti, Zr, Hf), 5 (V, Nb, Ta), and 6 (Cr, Mo, W).

[0690] The metal sheets in the sheet crucible preferably comprise a sintered metal selected from the group consisting of molybdenum, tungsten, or combinations thereof. The metal sheets in the sheet crucible also preferably comprise at least one other refractory metal, particularly preferably rhenium, osmium, iridium, ruthenium, or combinations of two or more thereof.

[0691] The metal sheet in the sheet crucible preferably comprises an alloy of molybdenum and a refractory metal, or tungsten and a refractory metal. Particularly preferred alloy metals are rhenium, osmium, iridium, ruthenium, or combinations thereof. According to another example, the metal sheet in the sheet crucible is an alloy of molybdenum and tungsten, rhenium, osmium, iridium, ruthenium, or combinations thereof. For example, the metal sheet in the sheet crucible is an alloy of tungsten and molybdenum, rhenium, osmium, iridium, ruthenium, or combinations thereof.

[0692] The metal sheets in the aforementioned sheet crucible may preferably be coated with a refractory metal. According to one example, the metal sheets in the sheet crucible are coated with rhenium, osmium, iridium, ruthenium, molybdenum, and tungsten, or a combination of two or more thereof.

[0693] The metal sheets and coatings preferably have different compositions. For example, the molybdenum metal sheet is coated with any combination of rhenium, osmium, iridium, ruthenium, tungsten, or two or more of them. According to another example, the tungsten metal sheet is coated with one or more layers of rhenium, osmium, iridium, ruthenium, molybdenum, or two or more of them. According to another example, the metal sheet in the metal sheet crucible may contain molybdenum alloyed with rhenium or tungsten alloyed with rhenium, and the interior of the crucible may be coated with one or more layers containing any combination of rhenium, osmium, iridium, ruthenium, or two or more of them.

[0694] The metal sheets in the suspended sheet crucible preferably have a density of 95% or higher than the theoretical density, for example, 95% to 98% or 96% to 98% of the theoretical density. More preferably, a higher theoretical density is particularly in the range of 98% to 99.95%. The theoretical density of the working material is equal to the density of 100% dense material without pores. A density greater than 95% of the metal sheets in the sheet material can be obtained, for example, by sintering sintered metal and then compressing the sintered material. Particularly preferably, the sheet crucible can be obtained by sintering sintered metal to obtain metal sheets and processing the metal sheets to form the crucible.

[0695] Metal sheet crucibles preferably have at least a lid, walls, and a base metal sheet. Suspended metal sheet crucibles preferably have at least one, for example at least two, three, or four, and particularly preferably at least five or all of the following characteristics:

[0696] (a) At least one layer, for example more than one layer, or at least two layers, or at least three layers, or at least five layers, particularly preferably three or four layers of metal sheets;

[0697] (b) At least one metal sheet, for example at least three, or at least four, or at least six, or at least eight, or at least twelve, or at least 15, or at least 16, or at least 20 metal sheets, particularly preferably twelve or 16 metal sheets;

[0698] (c) At least one combination of two metal sheet segments, for example, at least two, or at least five, or at least ten, or at least 18, or at least 24, or at least 36, or at least 48, or at least 60, or at least 72, or at least 48, or at least 96, or at least 120, or at least 160, with a particular preference for combinations of 36 or 48;

[0699] (d) By deep drawing, for example by a combination of deep drawing and fixed metal sheet, or by digging, bolting or welding, for example by electron beam welding and sintering welding, particularly preferably riveting, the metal sheet sections of the suspended metal sheet crucible are riveted into, for example, at least one combination.

[0700] (e) The metal sheet in the suspended metal sheet crucible can be obtained by reforming in combination with increasing physical density, preferably by reforming sintered metal or sintered alloy; further preferred is reforming rolling;

[0701] (f) Suspension made of copper, aluminum, steel, nickel or refractory metal, such as crucible material, preferably a water-cooled suspension made of copper or steel;

[0702] (g) Nozzle, preferably a nozzle that is permanently connected to the crucible;

[0703] (h) Mandrel, such as a mandrel connected to a nozzle via a step, a mandrel attached to a lid via a handle, or a mandrel connected to the bottom of a crucible via a handle;

[0704] (i) At least one gas inlet, for example in the form of a filling pipe or as a separate inlet;

[0705] (j) At least one gas outlet, for example in the form of a separate outlet on the lid or in the wall of the crucible;

[0706] (k) Cooling jacket, preferably a water-cooled jacket;

[0707] (l) Insulated from the outside, preferably insulated from an outside made of zirconium oxide.

[0708] Suspended sheet crucibles can, in principle, be heated by any means familiar to the technician and deemed suitable therein. Suspended sheet crucibles can be heated by means of an electric heating element (resistance) or by induction. In resistance heating, the solid surface of the sheet crucible is heated from the outside and energy is transferred from there to its interior. In induction heating, energy is directly connected and transferred from there to the interior of the furnace by rushing into the side wall of the melting furnace. In the case of resistance heating, energy is connected by radiation, where the solid surface is heated from the outside and energy is transferred from there to its interior. Molten crucibles are preferably induction heated.

[0709] According to another embodiment of the invention, energy is not input into the molten crucible, or in particular, to melt the melt, by means of a flame (e.g., a burner flame directed into or at the molten crucible), but rather by heating the molten crucible or the melt therein, or both. According to another embodiment, no burner is provided to melt the melt.

[0710] The suspended metal sheet crucible can be moved within the furnace via a suspended arrangement. Preferably, the crucible can at least partially enter and exit the furnace. If different heating zones exist within the furnace, their temperature distribution will be transferred to the crucible within the furnace: therefore, changing the position of the crucible within the furnace can create multiple heating zones, variable heating zones, or multiple variable heating zones within the crucible.

[0711] The sheet metal crucible has a nozzle. The nozzle is formed of a nozzle material. The nozzle material preferably comprises a pre-compressed material, for example, based on the theoretical density of the nozzle material in each case, having a density greater than 95%, for example 98% to 100%, particularly preferably 99% to 99.999%. The nozzle material preferably contains a refractory metal, such as molybdenum, tungsten, or a combination thereof with another refractory metal. Molybdenum is particularly preferred as a nozzle material. A nozzle containing molybdenum may preferably have a density of 100% of its theoretical density.

[0712] The base metal sheet contained in the sheet crucible is preferably thicker than the sides of the sheet crucible. The base metal sheet is preferably made of the same material as the sides of the sheet crucible. The base metal sheet of the sheet crucible is preferably not a rolled metal sheet. In each case, based on the wall thickness of the sheet crucible, the base metal sheet is, for example, 1.1 to 5000 times thicker, 2 to 1000 times thicker, or 4 to 500 times thicker.

[0713] According to another embodiment, the furnace includes a suspended or vertical filter crucible into which silica particles are fed and heated to obtain a glass melt.

[0714] A sintered crucible refers to a crucible made of sintered material containing sintered metal and having a density not exceeding 96% of the theoretical density of the metal. Sintered metal refers to a metal or alloy obtained by sintering metal powder. The sintered material and sintered metal in the sintered crucible are not rolled.

[0715] The sintering material of the sintering crucible preferably has a density of 85% or higher than the theoretical density of the sintering material, for example, 85% to 95% or 90% to 94%, and particularly preferably 91% to 93%.

[0716] Sintering materials may, in principle, include any and all materials known to those skilled in the art and suitable for molten silica. The sintered metal is preferably made from at least one of elements selected from the group consisting of refractory metals, graphite, or a material formed by hammering graphite foil.

[0717] The sintering material preferably comprises a first sintering metal selected from the group consisting of molybdenum, tungsten, or combinations thereof. More preferably, the sintering material further comprises at least one other refractory metal besides the first sintering metal, particularly preferably selected from the group consisting of molybdenum, tungsten, rhenium, osmium, iridium, ruthenium, or combinations of two or more thereof.

[0718] The sintering material preferably comprises an alloy of molybdenum and a refractory metal or tungsten and a refractory metal. Particularly preferred alloying metals are rhenium, osmium, iridium, ruthenium, or combinations thereof. According to another example, the sintering material comprises an alloy of molybdenum and tungsten, rhenium, osmium, iridium, ruthenium, or combinations thereof. For example, the sintering material comprises an alloy of tungsten and molybdenum, rhenium, osmium, iridium, ruthenium, or combinations thereof.

[0719] According to another embodiment, the sintered material may include a coating containing refractory metals, particularly rhenium, osmium, iridium, ruthenium, or combinations thereof. According to one example, the coating comprises rhenium, osmium, iridium, ruthenium, molybdenum, and tungsten, or combinations thereof.

[0720] The sintering material and its coating preferably have different compositions. For example, a sintering material containing molybdenum is coated with one or more layers of rhenium, osmium, iridium, ruthenium, tungsten, or any combination of two or more thereof. According to another example, a sintering material containing tungsten is coated with one or more layers of rhenium, osmium, iridium, ruthenium, molybdenum, or any combination of two or more thereof. According to yet another example, the sintering material may contain molybdenum alloyed with rhenium or tungsten alloyed with rhenium, and the interior of the crucible may be coated with one or more layers containing rhenium, osmium, iridium, ruthenium, or any combination of two or more thereof.

[0721] Preferably, the sintering crucible is made by sintering the sintering material. The sintering crucible can be integrally formed. It is also possible to manufacture individual components of the sintering crucible in a mold and then process them to obtain the sintering crucible. The crucible is preferably made of more than one component, for example, a base metal sheet and one or more side components. The side components are preferably integrally formed based on the circumference of the crucible. The sintering crucible can preferably be made of multiple side components arranged above each other. The side components of the sintering crucible are preferably sealed by bolting or by tongue and groove connections. Bolting is preferably accomplished by manufacturing side components with threads at the edges. In tongue and groove connections, the two side components to be connected each have a groove at the edge, and a tenon is inserted into the groove as a connecting third component, thereby forming a flush connection perpendicular to the horizontal plane of the crucible wall. Particularly preferably, the sintering furnace is made of more than one side component, for example, two or more side components, particularly preferably one or more side components. Particularly preferably, the components of a suspended sintering crucible are bolted together. Particularly preferably, the components of the vertical sintering crucible are connected by means of tenon and mortise joints.

[0722] The base metal sheet can, in principle, be attached to the crucible wall in any manner known to those skilled in the art as suitable for this purpose. According to one embodiment, the base metal sheet is provided with external threads and is attached to the crucible wall by bolting the base metal sheet to the crucible wall. According to another embodiment, the base metal sheet is attached to the crucible wall by means of bolts. According to another embodiment, the base metal sheet is suspended in the sintering crucible, for example, by placing the base metal sheet on an inner flange on the crucible wall. According to another embodiment, at least a portion of the crucible wall and the thickened base metal sheet are sintered together. Particularly preferably, the base metal sheet and the crucible wall of a suspended sintering crucible are bolted together. Particularly preferably, the base metal sheet and the crucible wall of a vertical sintering crucible are connected by means of a tongue and groove joint.

[0723] The base metal sheet contained in the sintering crucible is preferably thicker than the sides, for example, 1.1 to 20 times thicker, or 1.2 to 10 times thicker, or 1.5 to 7 times thicker, and particularly preferably 2 to 5 times thicker. Preferably, the sides of the sintering crucible have a constant wall thickness along both the circumference and height.

[0724] The sintering furnace has nozzles. The nozzles are formed from nozzle material. The nozzle material preferably comprises a pre-compressed material, for example, based on the theoretical density of the nozzle material in each case, having a density greater than 95%, for example 98% to 100%, particularly preferably 99% to 99.999%. The nozzle material preferably contains refractory metals, such as molybdenum, tungsten, or combinations thereof. Molybdenum is particularly preferred as a nozzle material. Nozzles containing molybdenum may preferably have a density of 100% of the theoretical density.

[0725] Suspended sintering crucibles can, in principle, be heated in any manner familiar to the technician and that appears suitable for their purpose. Vertical sintering crucibles can be heated, for example, by induction heating or resistance heating. In the case of induction heating, energy is directly input into the sidewalls of the sintering crucible via coils and from there transferred to the interior of the crucible. In the case of resistance heating, energy is input via radiation, where the solid surface is heated from the outside and energy is transferred from there to its interior. Sintering furnaces are preferably induction heated.

[0726] According to another embodiment of the invention, energy is not input into the molten crucible, or in particular, to melt the melt, by means of a flame (e.g., a flame in the molten crucible or a burner flame directed at the molten crucible), but rather by heating the molten crucible or the melt it contains, or both.

[0727] Preferably, the sintering crucible has one or more heating zones, such as one, two, three, or more than three heating zones, preferably one, two, or three heating zones, particularly one heating zone. The heating zones of the sintering crucible can be made to reach the same or different temperatures. For example, all heating zones can be made to reach one temperature, or all heating zones can be made to reach different temperatures, or two or more heating zones can be made to reach one temperature while one or more heating zones reach other temperatures independently of each other. Preferably, all heating zones are made to reach different temperatures, for example, the temperature of the heating zones increases along the transport direction of the silica particles.

[0728] Suspended sintering crucibles refer to the aforementioned type of sintering crucibles that are suspended in the furnace.

[0729] The suspended sintering crucible preferably has at least one of the following characteristics, for example, at least two, at least three, or at least four, and particularly preferably all of them:

[0730] {a} Suspension, preferably a height-adjustable suspension;

[0731] {b} At least two sealing rings serve as side components, preferably at least two rings bolted together as side components;

[0732] {c} Nozzle, preferably a nozzle permanently attached to the crucible;

[0733] {d} Mandrel, such as a mandrel attached to a nozzle via a step, a mandrel attached to a lid via a handle, or a mandrel connected to the bottom of a crucible via a handle;

[0734] {e} At least one gas inlet, for example in the form of a filling tube or in the form of at least one gas inlet, for example in the form of a filling tube or in the form of a separate inlet, particularly preferably in the form of a filling tube;

[0735] {f} At least one gas outlet, for example, in the lid or wall of the crucible.

[0736] {g} Cooling jacket, water cooling jacket is preferred;

[0737] The insulation on the outside of the crucible, such as the outside of the cooling jacket, is preferably made of zirconium oxide.

[0738] A preferred suspension is one that is fixed during the manufacture of a suspended sintering crucible, such as a suspension of the sintering material provided as an integral part of the crucible. Another preferred suspension is one fixed to the sintering crucible by a material other than the sintering material, such as aluminum, steel, iron, nickel, or copper, preferably copper, and particularly preferably a suspension fixed to the cooling system of the sintering crucible, such as a water-cooled copper suspension.

[0739] Suspended sintering crucibles can be moved within a furnace by means of a suspended arrangement. The crucibles can preferably enter and exit the furnace at least partially. If different heating zones exist within the furnace, their temperature distribution will be transferred to the crucibles within the furnace: therefore, changing the position of the crucible within the furnace can create multiple heating zones, varying heating zones, or multiple variations of heating zones within the crucible.

[0740] Vertical sintering crucibles refer to the above-mentioned type of sintering crucibles that are arranged vertically in a furnace.

[0741] Vertical sintering crucibles preferably have at least one of the following characteristics, such as at least two, at least three, or at least four, and particularly preferably all of them:

[0742] The area formed as a vertical surface is preferably a vertical surface formed at the bottom of the crucible, more preferably a vertical surface formed in the base metal sheet of the crucible, and particularly preferably a vertical surface formed at the outer edge of the bottom of the crucible.

[0743] / b / At least two sealing rings are used as side components, preferably at least two rings sealed by mortise and tenon joints;

[0744] / c / Nozzle, preferably permanently attached to the furnace, particularly preferably a nozzle in an area of ​​the bottom of the crucible that does not form a vertical surface;

[0745] / d / mandrel, such as a mandrel attached to a nozzle via a step, or a mandrel attached to a lid via a step, or a mandrel connected to the bottom of the crucible via a handle;

[0746] / e / At least one gas inlet, for example in the form of a filling pipe or as a separate inlet;

[0747] / f / at least one gas outlet, for example in the form of a separate outlet on the lid or wall of the furnace;

[0748] / g / cover.

[0749] The vertical sintering crucible preferably has a gas chamber partitioned between the furnace and the area below the furnace. The area below the furnace refers to the region below the nozzle where the extracted molten glass is located. Preferably, the gas chamber is separated by the area where the crucible is located. Gas in the furnace gas chamber between the inner wall of the furnace and the outer wall of the crucible cannot escape downwards into the area below the furnace. The extracted molten glass does not come into contact with the gas from the furnace gas chamber. The surface purity of the molten glass extracted from a furnace with a vertical sintering crucible and the quartz glass produced therefrom is preferably higher than that of the molten glass extracted from a furnace with a suspended sintering crucible and the quartz glass produced therefrom.

[0750] In all preferred embodiments of the crucible, the crucible is connected to the inlet and outlet of the furnace, such that silica particles can enter the crucible via the crucible inlet and the furnace inlet and can be drawn out via the crucible outlet and the furnace outlet.

[0751] Adjacent to at least one inlet, the crucible has at least one opening, preferably multiple openings, through which gas can be fed in and out. The crucible preferably has at least two openings, at least one of which can be used as a gas inlet and at least one as a gas outlet. Using at least one opening as a gas inlet and at least one opening as a gas outlet preferably creates a gas flow within the crucible.

[0752] Silica particles are fed into the crucible through the crucible inlet and subsequently heated within the crucible. Heating can be carried out in the presence of one gas or a mixture of two or more gases. During heating, water adhering to the silica particles can enter the gas phase, thus forming another gas. The gas or mixture of two or more gases is located in the gas chamber of the crucible. Below the gas chamber of the crucible refers to the region inside the crucible not occupied by a solid or liquid phase. Suitable gases are, for example, hydrogen, inert gases, and two or more of these. "Inert gas" means those gases that do not react with the substance provided in the crucible at a temperature of up to 2400°C. Preferred inert gases are nitrogen, helium, neon, argon, krypton, and xenon, with argon and helium being particularly preferred. Heating is preferably carried out in a reducing atmosphere. This can preferably be provided by hydrogen or a combination of hydrogen and an inert gas (e.g., a combination of hydrogen and helium, or a combination of hydrogen and nitrogen, or a combination of hydrogen and argon, with a particular preference for a combination of hydrogen and helium).

[0753] Preferably, at least partial gas exchange of air, oxygen, and water with respect to hydrogen, at least one inert gas, or a combination of hydrogen and at least one inert gas is performed on the silica particles with respect to a combination of hydrogen and an inert gas. At least partial gas exchange of the silica particles occurs during injection, before heating, during heating, or during at least two of the aforementioned activities. Preferably, the silica particles are heated to melt in a gas stream of hydrogen and at least one inert gas (e.g., argon or helium).

[0754] Preferably, all embodiments of the furnace have a melting crucible and at least one gas inlet through which gas is fed into and drawn out during furnace operation. The furnace may also have at least one dedicated gas inlet. Alternatively or additionally, gas may be injected via a solid feed section (also referred to as a solid inlet), for example, together with silica particles, or before, after, or via a combination of both or more of the foregoing selections.

[0755] The furnace and gas flow are preferably characterized in combination with the features described in the first objective. The gas flow is preferably generated by injecting gas into the furnace through an inlet and drawing gas out of the furnace through an outlet. The term "gas exchange rate" refers to the volume of gas passing through the outlet from the furnace per unit time. The gas exchange rate is also called gas flow rate or volumetric flow rate.

[0756] The gas exchange rate of the gas flow is preferably in the range of 200 l / h to 3000 l / h, for example, 200 l / h to 2000 l / h, and particularly preferably in the range of 200 l / h to 1000 l / h.

[0757] The furnace temperature for melting silica particles is preferably in the range of 1700°C to 2500°C, for example in the range of 1900°C to 2400°C, and particularly preferably in the range of 2100°C to 2300°C.

[0758] The residence time in the furnace is preferably between 1 hour and 50 hours, for example, between 1 hour and 30 hours, and particularly preferably between 5 hours and 20 hours. In this context, "residence time" means the time required to remove the furnace filler from the melting furnace during the process of making the glass melt. The filler is the total mass of silica present in the melting furnace. Here, the silica can be present in solid form or in the form of glass melt.

[0759] The furnace temperature preferably increases longitudinally along the direction of material transport. The furnace temperature is preferably increased by at least 100°C along the direction of material transport, for example, at least 300°C, at least 500°C, or at least 700°C, and particularly preferably at least 1000°C. The maximum temperature in the furnace is preferably between 1700°C and 2500°C, for example, between 1900°C and 2400°C, and particularly preferably between 2100°C and 2300°C. The furnace temperature can be increased uniformly or according to a temperature characteristic diagram.

[0760] The furnace temperature is preferably reduced before the molten glass is removed from the furnace. The furnace temperature is preferably reduced by 50°C to 500°C, for example, 100°C or 400°C, and particularly preferably by 150°C to 300°C, before the molten glass is removed from the furnace. The temperature of the molten glass at the time of removal is preferably 1750°C to 2100°C, for example, 1850°C to 2050°C, and particularly preferably 1900°C to 2000°C.

[0761] The furnace temperature preferably decreases along the length of the material transport direction and before the molten glass is removed from the furnace. The furnace temperature is preferably decreased by at least 100°C along the length of the material transport direction, for example, at least 300°C, at least 500°C, or at least 700°C, particularly preferably at least 1000°C. The maximum temperature in the furnace is 1700°C to 2500°C, for example, 1900°C to 2400°C, particularly preferably 2100°C to 2300°C. The furnace temperature is preferably decreased by 50°C to 500°C, for example, 100°C or 400°C, particularly preferably 150°C to 300°C, before the molten glass is removed from the furnace.

[0762] Preheating section

[0763] The furnace preferably has at least a first chamber and another chamber connected to each other by a passage, wherein the first chamber and the other chamber are at different temperatures, with the temperature of the first chamber being lower than that of the other chamber. In the other chamber, glass melt is formed from silica particles. This chamber is referred to below as the melt chamber. A chamber connected to the melting chamber via a material feed section but upstream therefrom is also called a preheating section. An example is a chamber with at least one outlet directly connected to the inlet of the melting chamber. The arrangement of the invention can also be formed in a separate furnace, in which case the melting chamber is the melting furnace. However, for the purposes of further description, the melting oven and the melting chamber can be synonymous: therefore, what is described with respect to the melting furnace also applies to the melting chamber, and vice versa. The term "preheating section" is the same in either case.

[0764] The silica particles are preferably introduced into the furnace at a temperature in the range of 20°C to 1300°C.

[0765] According to the first embodiment, the silica particles are not tempered before entering the melting chamber. The silica particles enter the furnace at a temperature, for example, in the range of 20°C to 40°C, particularly preferably 20°C to 30°C. If silica particles II are prepared according to step i.), they preferably enter the furnace at a temperature in the range of 20°C to 40°C, particularly preferably 20°C to 30°C.

[0766] According to another embodiment, the silica particles are tempered to a temperature ranging from 40°C to 1300°C before entering the furnace. Tempering means setting the temperature to the selected value. Tempering can, in principle, be carried out by any and all methods known to those skilled in the art for tempering silica particles. For example, tempering can be carried out in a furnace arranged separately from the melting chamber or in a furnace connected to the melting chamber.

[0767] Tempering is preferably carried out in a chamber connected to the melting chamber: that is, the furnace includes a preheating section in which the silica can be tempered. Preferably, the preheating section itself is a mobile furnace, particularly a rotary furnace. A rotary furnace refers to a heating chamber that moves silica from the inlet to the outlet of the mobile furnace during operation. The outlet is preferably directly connected to the inlet of the melting furnace, so that silica particles can be transferred from the preheating section to the melting furnace without any other intermediate steps or activities.

[0768] The preheating section preferably has at least one gas inlet and at least one gas outlet. Gas can reach the interior, the gas chamber of the preheating section, through the gas inlet; and it can exit through the gas outlet. Gas may also be injected into the preheating section via inlet silica particles. Similarly, the gas can be discharged through the preheating section outlet and then separated from the silica particles. Preferably, gas can be fed into the preheating section via both the silica particle inlet and the gas inlet, and discharged via both the preheating section outlet and the preheating section gas outlet.

[0769] The use of gas inlets and outlets preferably generates a gas flow in the preheating section. Suitable gases are hydrogen, inert gases, and two or more of them. Preferred inert gases are nitrogen, helium, neon, argon, krypton, and xenon, with nitrogen and helium being particularly preferred. The preheating section preferably has a reducing atmosphere. This can preferably be provided by hydrogen or a combination of hydrogen and an inert gas (e.g., a combination of hydrogen and helium, or a combination of hydrogen and nitrogen, with a particular preference for a combination of hydrogen and helium). The preheating section also preferably has an oxidizing atmosphere. This can preferably be provided by oxygen or a combination of oxygen with one or more other gases, with air being particularly preferred. It is also preferable that silica be tempered under reduced pressure in the preheating section.

[0770] For example, silica particles have a temperature in the range of 100°C to 1100°C, 300°C to 1000°C, or 600°C to 900°C when they enter the furnace.

[0771] According to the embodiment of the first objective, the furnace includes at least two chambers. The furnace preferably includes a first chamber and at least one other chamber. The first chamber and the other chamber are connected to each other via a passageway.

[0772] At least two chambers in the furnace can be arranged, preferably vertically or horizontally, but particularly preferably vertically, as needed. The chambers in the furnace are preferably arranged such that, during the process according to the first objective, silica particles pass through the first chamber and then through the other chamber to obtain a glass melt. The other chamber preferably has the characteristics of the melting furnace and the crucible arranged therein as described above.

[0773] Preferably, each of the chambers has an inlet and an outlet. The furnace inlet is preferably connected via a passage to the inlet of the first chamber. The furnace outlet is preferably connected via a passage to the outlet of the other chamber. The outlet of the first chamber is preferably connected via a passage to the inlet of the other chamber.

[0774] The first chamber is preferably arranged in a furnace such that silica particles can reach the first chamber. The second chamber is preferably arranged in a furnace such that molten silica glass can be removed from the third chamber via the furnace outlet. Particularly preferably, silica particles can reach the first chamber via the furnace inlet, and molten silica can be removed from the third chamber via the furnace outlet.

[0775] Silica, in granular or powder form, can enter from the first chamber into the other chamber via a channel along the material transport direction specified in the method. The chambers connected via the channel include arrangements in which other elements are arranged along the material transport direction between the first and other chambers. Gases, liquids, and solids can, in principle, pass through the channel. Silica powder, suspensions of silica powder, and silica particles can preferably pass through the transition section between the first and other chambers. While performing the procedure according to the invention, all substances input into the first chamber can enter the other chamber via the channel between the first and other chambers. Preferably, only silica in granular or powder form enters the other chamber via the channel. Preferably, the channel between the first and other chambers is sealed with silica, such that the gas chambers of the first and other chambers are separated from each other, preferably such that the gas chambers can contain different gases or gas mixtures, different pressures, or both. According to another embodiment, the channel is formed by a sluice gate, preferably a perforated wheeled sluice gate.

[0776] The first chamber of the furnace preferably has at least one gas inlet and at least one gas outlet. The gas inlet can, in principle, take any form known to a person skilled in the art and suitable for injecting gas, such as a nozzle, valve, or pipe. The gas outlet can, in principle, take any form known to a person skilled in the art and suitable for exiting gas, such as a nozzle, valve, or pipe.

[0777] Preferably, the silica particles are fed into the first chamber via the furnace inlet and heated, and can be heated in the presence of one or a combination of two or more gases. For this purpose, the gas or a combination of two or more gases is in the first chamber. The gas chamber of the first chamber refers to the region of the first chamber not occupied by a solid or liquid phase. Suitable gases are, for example, hydrogen, oxygen, inert gases, or two or more of the above. Preferred inert gases are nitrogen, helium, neon, argon, krypton, and xenon, with nitrogen, helium, or combinations thereof being particularly preferred. Heating is preferably carried out in a reducing atmosphere. This can preferably be provided by hydrogen or a combination of hydrogen and helium. The silica particles are preferably heated in the first chamber in a gas stream or in a combination of two or more gases.

[0778] More preferably, the silica particles are heated in the first chamber under reduced pressure, for example at a pressure of less than 500 mbar or less than 300 mbar, such as 200 mbar or less.

[0779] Preferably, the first chamber is provided with at least one device for moving the silica particles. In principle, any and all devices known to those skilled in the art and appearing suitable for this purpose may be selected. A stirring, shaking, or oscillating device is preferred.

[0780] According to another embodiment, the temperatures in the first chamber and the other chamber are different. The temperature in the first chamber is preferably lower than the temperature in the other chamber. The temperature difference between the first chamber and the other chamber is preferably in the range of 600°C to 2400°C, for example, in the range of 1000°C to 2000°C or 1200°C to 1800°C, and particularly preferably in the range of 1500°C to 1700°C. Furthermore, the temperature in the first chamber is preferably 600°C to 2400°C lower than the temperature in the other chamber, for example, 1000°C to 2000°C or 1200°C to 1800°C, and particularly preferably 1500°C to 1700°C.

[0781] According to another embodiment, the first chamber of the furnace is a preheating section, particularly preferably a preheating section with the aforementioned characteristics as described above. The preheating section is preferably connected to the first chamber via a channel. Silica from the preheating section preferably enters another chamber via the channel. The channel between the preheating section and the other chamber can be closed, preventing gas injected into the preheating section from entering the other chamber. With the channel closed, the silica does not come into contact with water. The channel between the preheating section and the other chamber can be closed, separating the gas chambers of the preheating section and the first chamber from each other, allowing the gas chambers to contain different gases or gas mixtures or both. The preferred channel is the one described above.

[0782] According to another embodiment, the first chamber of the furnace is not a preheating section. For example, the first chamber is an equalization chamber. An equalization chamber refers to a chamber in the furnace where variations in throughput in the upstream preheating section or differences in throughput between the preheating section and another chamber are equalized. For example, as described above, a rotary furnace can be located upstream of the first chamber. This typically has a throughput variation of up to 6% of the average throughput. The silica is preferably maintained in the equalization chamber at its temperature upon entering.

[0783] The furnace may also have a first chamber and more than one other chamber, such as two, three, four, five or more than five other chambers, with two other chambers being particularly preferred. If the furnace has two other chambers, the first chamber is preferably a preheating section, and based on the material transport direction, the first chamber of the other chambers is an equalization chamber and the second chamber of the other chambers is a melting chamber.

[0784] According to another embodiment, the additive is present in the first chamber. The additive is preferably selected from the group consisting of halogens, inert gases, bases, oxygen, or combinations of two or more of the above.

[0785] Suitable additives are, in principle, halogens and halogen compounds in elemental form. Halogens are preferably selected from the group consisting of chlorine, fluorine, chlorine compounds, and fluorine compounds. Elemental chlorine and hydrogen chloride are particularly preferred.

[0786] Suitable additives are, in principle, all inert gases and mixtures of two or more of them. Preferred inert gases are nitrogen, helium, or combinations thereof.

[0787] In principle, alkalis are also suitable additives. Organic and inorganic alkalis are preferred as additives.

[0788] Oxygen is also suitable as an additive. Oxygen is preferably present in an oxygen-based atmosphere, for example, in combination with one inert gas or a mixture of two or more inert gases, and particularly preferably in combination with nitrogen, helium or nitrogen and helium.

[0789] The first chamber may, in principle, contain any material known to those skilled in the art suitable for heating silicon dioxide. The first chamber preferably contains at least one element selected from the group consisting of: quartz glass, refractory metals, aluminum, and combinations of two or more thereof; the first chamber preferably contains quartz glass or aluminum.

[0790] Preferably, if the first chamber contains a polymer or aluminum, the temperature in the first chamber does not exceed 600°C. If the first chamber contains quartz glass, the temperature in the first chamber is preferably between 100°C and 1100°C. The first chamber preferably contains substantially quartz glass.

[0791] When silica is transported from one chamber to another through a channel between the two chambers, the silica can, in principle, be in any desired state. Silica is preferably in solid form, such as in the form of particles, powder, or granules. According to one embodiment of the first objective, silica is transported from the first chamber to the second chamber in granular form.

[0792] According to another embodiment, the other chamber is a crucible made of metal sheets or sintered material containing sintered metal, wherein the metal sheets or sintered metal are selected from the group consisting of molybdenum, tungsten, or combinations thereof.

[0793] Measuring dew point

[0794] Dew point refers to a temperature below which a portion of the gas or gas mixture under test condenses without changing the pressure. This typically refers to the condensation of water. Dew point is determined according to the test method described in the Methods section.

[0795] According to the present invention, the dew point of the gas is below 0°C when it leaves the furnace via the gas outlet.

[0796] According to the invention, the furnace, preferably the melting crucible, contains at least one gas outlet through which gas is injected into the furnace and drawn off during furnace operation. The furnace may also have at least one dedicated gas outlet. Alternatively or additionally, gas may be injected via a solid feed section (also called a solid inlet), for example, together with silica particles, or before, after, or via a combination of both or more of the aforementioned options.

[0797] According to the invention, when the gas extracted from the furnace leaves the oven via the gas outlet, it has a dew point below 0°C, for example below -10°C or below -20°C. The dew point is determined at a slight overpressure of 5 mbar to 20 mbar according to the test method described in the Method section. A suitable test apparatus is, for example, the "Optidew" apparatus from Michell Instruments GmbH, D-61381 Friedrichsdorf.

[0798] The dew point of the gas is preferably measured at a point 10 cm or more away from the gas outlet of the furnace. This distance is typically between 10 cm and 5 m. Within this range (described here as "at the outlet"), the distance of the measuring point from the gas outlet of the furnace is irrelevant to the dew point measurement result. The gas is fed from the outlet to the measuring point via a liquid means, such as in a hose or pipe. The temperature of the gas at the measuring point is typically between 10°C and 60°C, for example, between 20°C and 50°C, particularly between 20°C and 30°C.

[0799] Suitable gases and gas mixtures have been described. During testing, it has been found that the above data applies to each of the gases and gas mixtures.

[0800] According to another preferred embodiment, the gas or gas mixture has a dew point below -50°C, for example below -60°C, or below -70°C, or below -80°C, before entering the furnace, particularly the molten crucible. The dew point typically does not exceed -60°C. The following dew point ranges are also preferred when entering the furnace: -50°C to -100°C, -60°C to -100°C, and -70°C to -100°C.

[0801] According to another preferred embodiment, the dew point of the gas before entering the furnace is at least 30°C lower than when it exits the furnace, for example, at least 50°C, 60°C, or even 80°C lower. This data applies when measuring the dew point exiting the furnace. It also applies when measuring the dew point before entering the furnace. Since no source of increased humidity is provided and there is no possibility of condensation between the measurement point and the furnace, the distance from the measurement point to the gas inlet of the furnace is irrelevant here.

[0802] According to the preferred embodiment, the furnace, particularly the molten crucible, operates at a gas exchange rate in the range of 200 l / h to 3000 l / h.

[0803] According to a preferred embodiment, the melting crucible is at least partially formed of a material comprising one or more metals selected from molybdenum, tungsten, rhenium, iridium, and osmium.

[0804] According to a preferred embodiment, the quartz glass contains one or more metals selected from molybdenum, tungsten, rhenium, iridium, and osmium, totaling less than 1000 ppb, based on the total weight of the quartz glass.

[0805] According to a preferred embodiment, the dew point is determined in the test unit, which is separated from the gas exiting from the gas outlet by a membrane. The membrane is preferably permeable to moisture. This protects the test unit from any amount of dust and other particles transmitted from the melting furnace (particularly the molten crucible) in the gas stream. This measure significantly extends the working life of the test probes. Working life refers to the span of time during which the test probes do not need to be replaced or cleaned while operating the furnace.

[0806] According to the preferred embodiment, a dew point measuring device or a dew point level hygrometer is used.

[0807] In one embodiment of the first objective, the molten energy for step vi.) is transferred to the silica particles via a solid surface. The selected silica particles are, for example, compressed silica particles.

[0808] "Solid surface" refers to a surface other than the surface of silica particles that does not melt or collapse when the silica particles are heated to their melting point. Suitable materials for solid surfaces include those suitable for use as crucible materials.

[0809] The solid surface can, in principle, be any surface known to a person skilled in the art and suitable for these purposes. The solid surface used can be the solid surface of the crucible or a separate component that is not part of the furnace.

[0810] Solid surfaces can, in principle, be heated by any means known to those skilled in the art and suitable for these purposes to transfer molten energy to the silica particles. Solid surfaces are preferably heated by resistance heating or induction heating. In the case of induction heating, energy is directly input into the solid surface via a coil and transferred from there to its interior. In the case of resistance heating, the solid surface is heated from the outside and energy is transferred from there to its interior, where a heating chamber gas with low heat capacity, such as an argon atmosphere or an argon-containing atmosphere, is advantageous. Solid surfaces can be heated, for example, electrically or by calcining the solid surface from the outside with a flame. Solid surfaces are preferably heated to a temperature that allows sufficient energy to be transferred to the silica particles and / or partially molten silica particles, reaching a temperature sufficient to melt the silica particles.

[0811] According to one embodiment of the invention, at least during step vi.), energy is not input into the crucible by means of heating the crucible or the melt contained therein, or both, by means of a flame (e.g., a burner flame directed into or onto the crucible).

[0812] If a single component is used as a solid surface, it can come into contact with the silica particles in any desired manner, such as by placing the component on the silica particles, inserting the component between the fine particles of silica, squeezing the component between the crucible and the silica particles, or by a combination of both or more of these methods. The component can be applied before, simultaneously with, or both before and simultaneously with the transfer of molten energy.

[0813] The molten energy is preferably transferred to the silica particles by heating the crucible to a point where the particles melt, via the interior of the crucible. The crucible is preferably heated by resistance or induction. Heat is transferred from the outside to the inside of the crucible. The solid surface inside the crucible transfers the molten energy to the silica particles.

[0814] According to another embodiment, molten energy is not transferred to the silica particles via the gas chamber. Furthermore, molten energy is not transferred to the silica particles by calcining them with a flame. Examples of these excluded energy transfer pathways include directing one or more burner flames from above into the melting furnace or onto the silica, or both.

[0815] Step vii.)

[0816] The molten glass is drawn out of the furnace via an outlet, preferably via a nozzle. The quartz glass body is formed from at least a portion of the molten glass, preferably by removing at least a portion of the molten glass prepared in step vi.).

[0817] The extraction of a portion of the glass melt prepared in step vi) can, in principle, be carried out continuously from the melting furnace or melting chamber, or immediately after the glass melt preparation is completed. It is preferable to extract a portion of the glass melt continuously. The glass melt is extracted from the furnace or melting chamber via an outlet, preferably via a nozzle in each case.

[0818] The molten glass can be cooled to a temperature suitable for glass formation before, during, or after its drawing. Cooling the molten glass increases its viscosity. The molten glass is preferably cooled to a point where the formed shape remains intact during molding, while molding can be performed as quickly and reliably as possible, and possibly with minimal energy. A technician can determine the viscosity of the molten glass by varying its temperature at the forming tool. The molten glass preferably has a temperature in the range of 1750°C to 2100°C, for example, 1850°C to 2050°C, and particularly preferably below 1900°C to 2000°C, at the time of drawing. After drawing, the molten glass is preferably cooled to a temperature below 500°C, for example, below 200°C, below 100°C, or below 50°C, and particularly preferably to a temperature in the range of 20°C to 30°C.

[0819] The resulting quartz glass body can be solid or hollow. A solid body means a body essentially composed of a single material, although a solid body may contain one or more inclusions, such as air bubbles. Such inclusions in a solid body are typically 65 mm in size. 3 Or smaller, for example, less than 40mm 3 or less than 20mm 3 or less than 5mm 3 or less than 2mm 3 Particularly preferred is a diameter less than 0.5mm. 3 In each case, based on the total volume of the solid body, the solid body preferably contains less than 0.02% by volume, for example less than 0.01% by volume or less than 0.001% by volume of its volume as inclusions.

[0820] Quartz glass has an external form. The term "external form" refers to the shape of the outer edge of the cross-section of the glass. The external form of quartz glass is preferably circular, elliptical, or a polygon with three or more angles, such as 4, 5, 6, 7, or 8 angles in cross-section; quartz glass is particularly preferred to be circular.

[0821] The length of the quartz glass body is preferably in the range of 100mm to 10000mm, for example, 1000mm to 4000mm, and particularly preferably in the range of 1200mm to 3000mm.

[0822] The quartz glass body preferably has an outer diameter in the range of 1 mm to 500 mm, for example, in the range of 2 mm to 400 mm, and particularly preferably in the range of 5 mm to 300 mm.

[0823] Quartz glass is formed using a nozzle. For this purpose, molten glass is fed through the nozzle. The external shape of the quartz glass formed by the nozzle is determined by the form of the opening in the nozzle. If the nozzle opening is circular, the quartz glass forms a cylinder during forming. If the nozzle opening has a specific structure, that structure is transferred to the external shape of the quartz glass. The quartz glass formed through a nozzle with a structured opening displays an image of this structure along the axial direction in terms of glass strain.

[0824] The nozzle is preferably integrated into the melting furnace as part of the crucible, and particularly preferably as part of the crucible outlet.

[0825] Preferably, at least a portion of the molten glass is drawn from the melting furnace via a nozzle. The external form of the quartz glass is formed by drawing at least a portion of the molten glass via a nozzle.

[0826] The quartz glass body is preferably cooled immediately after molding to maintain its shape. The quartz glass body is preferably cooled immediately after molding to a temperature at least 1000°C below the temperature of the glass melt during molding, for example, at least 1500°C or at least 1800°C, particularly preferably 1900°C to 1950°C. The quartz glass body is preferably cooled to a temperature below 500°C, for example, below 200°C, below 100°C, or below 50°C, particularly preferably to a temperature in the range of 20°C to 30°C.

[0827] According to one implementation scheme, the obtained quartz glass can be treated by at least one method selected from the group consisting of chemical treatment, heat treatment or mechanical treatment.

[0828] Chemical post-treatment of the quartz glass is preferred. Post-treatment involves the processing of the formed quartz glass. In principle, chemical post-treatment of the quartz glass means any method known to and appearing suitable for use by a person skilled in the art to alter the chemical structure or composition, or both, of the surface of the quartz glass. Chemical post-treatment preferably includes at least one measure selected from the group consisting of fluorine compound treatment and ultrasonic cleaning.

[0829] The fluorinated compounds discussed may in particular be hydrogen fluoride and fluoric acids, such as hydrofluoric acid. The liquid preferably has a fluorinated compound content in the range of 35% to 55% by weight, more preferably in the range of 35% to 45% by weight, based on the total fluid content in each case. The remainder, reaching 100% by weight, is typically water. The water selected is preferably fully desalinated or deionized water.

[0830] Ultrasonic cleaning is preferably performed in a fluid bath, and particularly preferably in the presence of a detergent. Fluorinated compounds such as hydrofluoric acid or hydrogen fluoride are typically not used in ultrasonic cleaning.

[0831] Ultrasonic cleaning of quartz glass is preferably performed under at least one, such as at least two, three, four, or five, and particularly preferably all of the following conditions:

[0832] - Ultrasonic cleaning is performed in a continuous process.

[0833] - The ultrasonic cleaning system has at least six chambers connected to each other by pipes.

[0834] - The residence time of the quartz glass in each chamber can be set. The residence time of the quartz glass in each chamber is preferably the same. The residence time in each chamber is preferably in the range of 1 min to 120 min, for example less than 5 min or 1 min to 5 min or 2 min to 4 min, or less than 60 min or 10 min to 60 min or 20 min to 50 min, and is particularly preferably in the range of 5 min to 60 min.

[0835] - The first chamber contains an alkaline medium, preferably containing water and alkali, and an ultrasonic cleaner.

[0836] - The third chamber contains an acidic medium, preferably containing water and acid, and an ultrasonic cleaner.

[0837] - The quartz glass body is cleaned with water, preferably desalinated water, in the second chamber and in the fourth to sixth chambers.

[0838] - Chambers four through six are operated under a spray of water, preferably desalinated water. Water is preferably injected only into chamber six, and from chamber six into chamber five, and from chamber five into chamber four.

[0839] It is preferable to perform heat post-treatment on the quartz glass. Heat post-treatment of the quartz glass generally means any measure known to a person skilled in the art that appears suitable for altering the quartz glass by influencing its form or structure, or both. Heat post-treatment preferably includes at least one of the following measures: tempering, stamping, gas filling, stretching, welding, or a combination of two or more thereof. Preferably, heat post-treatment is performed without the intention of removing material.

[0840] Tempering is preferably performed by heating the quartz glass in a furnace, preferably in the range of 900°C to 1300°C, for example, in the range of 900°C to 1250°C or 1040°C to 1300°C, and particularly preferably in the range of 1000°C to 1050°C or 1200°C to 1300°C. The heat treatment is preferably performed at a temperature not exceeding 1300°C for more than one hour, and particularly preferably at a temperature not exceeding 1300°C at any point during the entire heat treatment. Tempering can, in principle, be performed under reduced pressure, at atmospheric pressure, or under pressure, preferably under reduced pressure, and particularly preferably under vacuum.

[0841] The stamping is preferably performed by heating the quartz glass body, preferably to a temperature of about 2100°C, and then reshaping it during rotational motion, preferably at a speed of about 60 rpm. The rod-shaped quartz glass body can be reshaped into a cylinder, for example, by stamping.

[0842] Preferably, the quartz glass body can be inflated by blowing gas into it. For example, the quartz glass body can be inflated to form a large tube. For this purpose, preferably, the quartz glass body is heated to a temperature of about 2100°C, and then, during rotational motion at a speed of about 60 rpm, the internal space is flushed with gas, preferably at a defined and controlled internal pressure of up to about 100 mbar. A large tube refers to a tube with an outer diameter of at least 500 mm.

[0843] Preferably, the quartz glass body can be stretched by heating the quartz glass body, preferably to a temperature of about 2100°C, and then stretching the quartz glass body to the desired outer diameter at a controlled stretching speed. For example, a lamp tube can be made of quartz glass body.

[0844] Mechanical post-processing of the quartz glass is preferred. Post-processing of the quartz glass generally refers to any measure known to a person skilled in the art that appears suitable for altering the design of the quartz glass by dividing it into more than one piece through grinding. Specifically, mechanical post-processing includes at least one measure selected from the group consisting of: grinding, drilling, honing, sawing, water jet cutting, laser beam cutting, sandblasting roughening, or a combination of two or more of these.

[0845] Preferably, the quartz glass is treated with a combination of these measures, such as a combination of chemical and thermal post-treatment, or a combination of chemical and mechanical post-treatment, or a combination of thermal and mechanical post-treatment, with a combination of chemical, thermal, and mechanical post-treatment being particularly preferred. More preferably, the quartz glass can undergo more than one of the above-described measures, each of which is independent of the others.

[0846] According to another embodiment, the process may include the following optional process steps:

[0847] viii.) A hollow body formed from quartz glass with at least one opening.

[0848] The resulting hollow body has an internal form and an external form. "Internal form" refers to the shape of the inner edge of the hollow body as seen in cross-section. The internal and external forms of the hollow body's cross-section can be the same or different. The cross-sections of the hollow body's internal and external forms can be circular, elliptical, or polygonal with three or more corners, such as four, five, six, seven, or eight corners.

[0849] The external form of the cross-section preferably corresponds to the internal form of the cross-section of the hollow body. Particularly preferably, the cross-section of the hollow body has a circular internal form and a circular external form.

[0850] In another embodiment, the internal and external forms of the hollow body can be different from each other. The cross-section of the hollow body preferably has a circular external form and a polygonal internal form. Particularly preferably, the cross-section of the hollow body has a circular external form and a hexagonal internal form.

[0851] The length of the hollow body is preferably in the range of 100mm to 10000mm, for example, 1000mm to 4000mm, and particularly preferably in the range of 1200mm to 2000mm.

[0852] The hollow body preferably has a wall thickness in the range of 0.8 mm to 50 mm, for example, in the range of 1 mm to 40 mm, 2 mm to 30 mm, or 3 mm to 20 mm, and particularly preferably in the range of 4 mm to 10 mm.

[0853] The hollow body preferably has an outer diameter of 2.6 mm to 400 mm, for example, in the range of 3.5 mm to 450 mm, and particularly preferably in the range of 5 mm to 300 mm.

[0854] The hollow body preferably has an inner diameter of 1 mm to 300 mm, for example, in the range of 5 mm to 280 mm or 10 mm to 200 mm, and particularly preferably in the range of 20 mm to 100 mm.

[0855] The hollow body includes one or more openings. The hollow body preferably includes one opening. The hollow body preferably includes an even number of openings, such as 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20 openings. The hollow body preferably includes two openings. The hollow body is preferably a tube. This hollow body form is particularly preferred if the light guide includes only one core. The hollow body may include more than two openings. The openings are preferably located in pairs at the ends of the quartz glass body, opposite each other. For example, each end of the quartz glass body has 2, 3, 4, 5, 6, 7, or more than 7 openings, particularly preferably 5, 6, or 7 openings. Preferred forms are, for example, tubes, double tubes (i.e., tubes with two parallel channels), and multi-channel rods (i.e., tubes with more than two parallel channels).

[0856] Hollow bodies can be formed in principle by any means known to those skilled in the art. Hollow bodies are preferably formed by means of a nozzle. The nozzle preferably includes a means for drawing out molten glass during formation at the center of its opening. For example, hollow bodies can be formed from molten glass.

[0857] Hollow bodies can be formed by using a nozzle followed by post-processing. Suitable post-processing is, in principle, any and all methods known to those skilled in the art for manufacturing hollow bodies from solid bodies, such as stamping, drilling, honing, or grinding. A particularly preferred post-processing is to pass the solid body through one or more mandrels, thereby forming a hollow body. Mandrels can also be inserted into the solid body to form a hollow body. The hollow body is preferably cooled immediately after its formation.

[0858] After formation, the hollow body is preferably cooled immediately to a temperature below 500°C, for example, below 200°C, below 100°C, or below 50°C, and particularly preferably to a temperature in the range of 20°C to 30°C.

[0859] A second object of the present invention is a quartz glass body obtainable by one of the methods described in the first object. Correspondingly, a method for manufacturing a quartz body is also known, wherein steps i.) to vii.) are first performed.

[0860] In one embodiment, the quartz glass of one embodiment, the quartz glass for the second purpose, the quartz glass obtainable according to the first purpose, and the quartz glass obtainable according to the second purpose have at least one, preferably two or more, up to all of the following features:

[0861] A] Chlorine content less than 60 ppm;

[0862] B] Aluminum content less than 200 ppb;

[0863] C] Less than 5.10 19 / cm 3 For example, in 0.1·10 15 up to 3.10 15 / cm 3 Within the range, it is particularly preferred to be 0.5·10. 15 Up to 2.0.10 15 / cm 3 ODC content within the specified range;

[0864] D] The content of atoms other than Si, O, H and C is less than 5 ppm;

[0865] E] in log 10 (η(1250℃) / dPas)=11.4 to log 10 (η(1250℃) / dPas)=12.9, or log 10 (η(1300℃) / dPas)=11.1 to log 10 (η(1300℃) / dPas)=12.2, or log 10 (η(1350℃) / dPas)=10.5 to log 10 Viscosity in the range of (η(1350℃) / dPas)=11.5 (p=1013hPa);

[0866] F] less than 10 -4 The uniformity of refractive index;

[0867] G] Cylindrical shape;

[0868] Tungsten content less than 100 ppb, less than 40 ppb, less than 10 ppb, or less than 5 ppb;

[0869] I] Molybdenum content less than 100 ppb, less than 40 ppb, or less than 10 ppb, or less than 5 ppb, wherein at any time ppb and ppm are based on the total weight of the quartz glass.

[0870] A third objective of this invention is a method for manufacturing a light-protective component, the method comprising the following steps:

[0871] A / Provides a quartz glass body according to a second objective or an embodiment thereof, or a quartz glass body by means of a method according to a first objective, particularly by performing process steps i.) to vii.) according to the first objective;

[0872] The first step involves processing the quartz glass body to obtain a hollow body with at least one opening;

[0873] B / Insert one or more mandrels into the quartz glass body through at least one opening while retaining the precursor;

[0874] C / During heating, heat is drawn from the precursor in step B / to obtain an optical guide having one or more cores and a jacket M1.

[0875] Step A /

[0876] The quartz glass body provided in step A / is preferably characterized by the features of the first and second objectives of the invention. This quartz glass body can be obtained, in particular, by performing process steps i.) to vii.) according to the first objective of the invention. The quartz glass body can also be reshaped to obtain a hollow body having at least one opening. The quartz glass body thus obtained also has the features according to the fifth objective.

[0877] Step B /

[0878] One or more core rods are inserted through at least one opening in the quartz glass body (step B / ). In conjunction with the invention, a core rod refers to an article disposed in a jacket (e.g., jacket M1) and processed into a light guide. The core rod has a quartz glass core. Preferably, the core rod comprises a quartz glass core and a first jacket layer M0 surrounding the core.

[0879] Each mandrel has a form that is selected to fit the quartz glass body. The external form of the mandrel preferably corresponds to the form of the opening in the quartz glass body. Particularly preferably, the quartz glass body is a tube and the mandrel is a rod with a circular cross-section.

[0880] The diameter of the mandrel is smaller than the inner diameter of the hollow body. The diameter of the mandrel is preferably 0.1 mm to 3 mm smaller than the inner diameter of the hollow body, such as 0.3 mm to 2.5 mm smaller, or 0.5 mm to 2 mm smaller, or 0.7 mm to 1.5 mm smaller, and particularly preferably 0.8 mm to 1.2 mm smaller.

[0881] The ratio of the inner diameter of the quartz glass body to the diameter of the mandrel is preferably in the range of 2:1 to 1.0001:1, for example in the range of 1.8:1 to 1.01:1, or in the range of 1.6:1 to 1.005:1, or in the range of 1.4:1 to 1.01:1, particularly in the range of 1.2:1 to 1.05:1.

[0882] The areas inside the quartz glass not filled with the core rod are preferably filled with at least one other component, such as silica powder or silica particles.

[0883] The mandrel in the quartz glass can also be inserted into at least one other quartz glass, wherein the outer diameter of the other quartz glass is smaller than the inner diameter of the first quartz glass. The mandrel inserted into the quartz glass may also already be in two or more other quartz glass, for example, in three, four, five, six or more other quartz glass.

[0884] The quartz glass that can be obtained in this way, having one or more quartz glass bodies, is referred to below as the "precursor".

[0885] Step C /

[0886] The precursor is stretched while heated (step C / ). The resulting product is an optical guide having one or more cores and at least one jacket M1.

[0887] The stretching of the precursor is preferably performed at a speed in the range of 1 m / h to 100 m / h, for example, at a speed in the range of 2 m / h to 50 m / h or 3 m / h to 30 m / h. Particularly preferred is that the stretching of the quartz glass is performed at a speed in the range of 5 m / h to 25 m / h.

[0888] The stretching is preferably performed at a temperature of up to 2500°C, for example, at a temperature in the range of 1700°C to 2400°C, and particularly preferably at a temperature in the range of 2100°C to 2300°C.

[0889] The precursor is preferably guided through a furnace that heats the precursor from the outside.

[0890] The precursor is preferably extended or “stretched” until the desired thickness of the light guide is reached. Based on the length of the quartz glass body provided in step A / , the precursor is preferably stretched to 1,000 to 6,000,000 times its length, for example, 10,000 to 500,000 times its length or 30,000 to 200,000 times its length. Particularly preferably, based on the length of the quartz glass body in step A / , the precursor is preferably stretched to 100,000 to 10,000,000 times its length, for example, 150,000 to 5,800,000 times its length or 160,000 to 640,000 times its length or 1,440,000 to 5,760,000 times its length or 1,440,000 to 2,560,000 times its length.

[0891] The diameter of the precursor is preferably reduced by elongation in the range of 100 to 3,500, for example, in the range of 300 to 3,000 or 400 to 800 or 1,200 to 2,400 or 1,200 to 1,600, in each case based on the diameter gauge of the quartz glass body provided in step A / .

[0892] An optical waveguide (also known as an optical waveguide) may include any material suitable for conducting or guiding electromagnetic radiation, especially light.

[0893] Conducting or guiding radiation means extending radiation along the longitudinal extension of the optical guide without substantially impeding or attenuating its intensity, wherein the radiation is input into the optical guide via one end. The optical guide preferably conducts electromagnetic radiation in the wavelength range of 170 nm to 5000 nm. In each case, the optical guide preferably attenuates radiation in the wavelength range by 0.1 dB / km to 10 dB / km. The optical guide preferably has a transmission rate of up to 50 Tbit / s.

[0894] The optical guide preferably has a curling parameter greater than 6m. In this context, the curling parameter refers to the bending radius of a fiber that exists in the form of a freely movable fiber without external force, such as the optical guide or the jacket M1.

[0895] The light guide is preferably designed to be flexible. In the context of this invention, "flexible" means that the light guide is characterized by a bending radius of 20 mm or less, for example, 10 mm or less, and particularly preferably less than 5 mm or less. The bending radius refers to the narrowest radius that can be formed without breaking the light guide and without affecting its ability to conduct radiation. "Affect" means that the transmitted light is attenuated by more than 0.1 dB by bending the light guide. The attenuation is preferably stated at a reference wavelength of 1550 nm.

[0896] The light guide preferably has an elongated form. The form of the light guide is defined by its longitudinal extension L and its cross-section Q. The light guide preferably has a circular outer wall along its longitudinal extension L. The cross-section Q of the light guide is always defined by a plane perpendicular to the outer wall of the light guide. If the light guide is bent along its longitudinal extension L, the cross-section Q is determined by being perpendicular to the tangent at a point on the outer wall of the light guide. The light guide preferably has a diameter d in the range of 0.04 mm to 1.5 mm. L The optical guide preferably has a length ranging from 1m to 100km.

[0897] The optical guide may have one or more cores, such as one core, two cores, three cores, four cores, five cores, six cores, or more than seven cores, with one core being particularly preferred. Greater than 90%, for example, greater than 95%, and particularly preferably greater than 98%, of the electromagnetic radiation conducted through the optical guide is guided in the core. Light in one of the “preferred” wavelength ranges already stated for the optical guide is transmitted in the core. The material of the core is preferably selected from the group consisting of glass or quartz glass or a combination of both, with quartz glass being particularly preferred. The cores may be composed of the same or different materials independently of each other. All cores are preferably composed of the same material, and particularly preferably of quartz glass.

[0898] Each core has a preferred circular cross-section Q K And has a length L K The longitudinal form. The cross-section Q of the core. K The cross-section Q of any other core K Irrelevant. The cross-section Q of the core. K They can be the same or different. The cross-sectional area Q of all cores... K The preferred values ​​are the same. The core cross-section Q K It is always determined in a plane perpendicular to the outer wall of the core and / or the outer wall of the optical guide. If the core is bent along its longitudinal extension, the cross-section Q is... K The length L of the core is determined by a line perpendicular to the tangent at a point on the outer wall of the core. K With the length L of each other core K Irrelevant. Core length L K They can be the same or different. The length L of all cores... K The preferred characteristics are the same. Each core preferably has a length L ranging from 1m to 100km. K Each core has a diameter d. K The diameter d of a core K With the diameter d of each other core K Irrelevant. The diameter d of the core. K They can be the same or different. The diameter d of all cores... K The preferred values ​​are the same. The diameter d of each core is... KThe range is from 0.1 μm to 1000 μm, for example from 0.2 μm to 100 μm or from 0.5 μm to 50 μm, and particularly preferably from 1 μm to 30 μm.

[0899] Each core has at least one refractive in-dex running perpendicular to the maximum core elongation. The term "refractive in-dex running" means that the refractive index is constant or varies perpendicular to the maximum core elongation. A preferred refractive index running corresponds to a concentric refractive index profile, such as a concentric refractive index profile, wherein a first range with the maximum refractive index exists at the center of the core, connected by another range with a lower refractive index. Each core preferably has a length L... K The core has only one refractive index distribution. The refractive index distribution of the core is independent of the refractive index distribution of every other core. The refractive index distributions of the cores can be the same or different. Preferably, the refractive index distributions of all cores are the same. In principle, it is also possible for a core to have multiple different refractive index distributions.

[0900] Each refractive index distribution extending at a right angle to the maximum core has a maximum refractive index n. K Each refractive index distribution extending at a right angle to the maximum core can also have a lower refractoriness index. The lowest refractive index of the refractive index distribution is preferably greater than the maximum refractive index n of the refractive index distribution. K The minimum refractive index of the refractive index distribution should preferably be greater than the maximum refractive index n of the refractive index distribution. K The value is low, ranging from 0.0001 to 0.15, for example, from 0.0002 to 0.1, and particularly preferably from 0.0003 to 0.05.

[0901] The core preferably has a refractive index n in the range of 1.40 to 1.60, for example in the range of 1.41 to 1.59, and particularly preferably in the range of 1.42 to 1.58. K , in λ r The refractive index n of the core was measured at a reference wavelength of 589 nm (sodium D line), at a temperature of 20°C, and at a standard pressure of p = 1013 hPa (see the Test Methods section for more details). K The refractive index n of each of the other cores K Irrelevant. The refractive index n of the core. K They can be the same or different. The refractive index n of all cores. K The preferred option is the same.

[0902] Each core of the optical guide preferably has a density of 1.9 g / cm³. 3 Up to 2.5g / cm 3 Within a range, for example, at 2.0 g / cm³ 3 Up to 2.4 g / cm 3 Within the range, it is particularly preferred to be 2.1 g / cm³. 3Up to 2.3 g / cm 3 The density is within a certain range. The core preferably has a residual moisture content of less than 100 ppb, for example less than 20 ppb or less than 5 ppb, particularly preferably less than 1 ppb, based on the total weight of the core in each case. The density of the core is independent of the density of each other core. The core densities can be the same or different. It is preferred that all cores have the same density.

[0903] If the optical guide has more than one core, each core has the above-described characteristics independently of the other cores. Preferably, all cores have the same characteristics.

[0904] According to the invention, the core is surrounded by at least one sleeve M1. The sleeve M1 preferably surrounds the core along its total length. The sleeve M1 preferably surrounds at least 95%, for example at least 98% or at least 99%, and particularly preferably 100% (i.e., the entire outer wall) of the outer surface of the core. The sleeve M1 preferably completely surrounds the core up to its ends (the last 1-5 cm of each core). This serves to protect the core from mechanical stress.

[0905] Jacket M1 may contain a cross section Q with a refractive index lower than that of the core. K The process point P is any material containing silicon dioxide. This is preferably the cross-section Q of the core. K At least one point in the process, located at the center of the core. More preferably, at the cross-section Q of the core. K Point P in the process is the core with the highest refractive index n. Kmax The point. Preferably, the refractive index n of the jacket M1. M1 The refractive index n of the core at at least one point during the process of cross-section Q of the core. K The refractive index n is at least 0.0001. Preferably, the refractive index n of the jacket M1 is... M1 The refractive index n of the core K The value is low in the range of 0.0001 to 0.5, for example in the range of 0.0002 to 0.4, and particularly preferably in the range of 0.0003 to 0.3.

[0906] The jacket M1 preferably has a refractive index n in the range of 0.9 to 1.599, for example in the range of 1.30 to 1.59, and particularly preferably in the range of 1.40 to 1.57. M1 The jacket M1 is preferably formed with a constant refractive index n. M1 The optical guiding region. A range with a constant refractive index means the range in which the refractive index is relative to the average refractive index n within that range. M1 The area where the change does not exceed 0.0001.

[0907] The optical guide may, in principle, include other jackets. Particularly preferably, at least one, or more than one, jacket has a refractive index less than the refractive index n of each core.K The optical guide preferably has one, two, three, four, or more than four jackets surrounding the jacket M1. Preferably, the refractive index of the other jackets surrounding the jacket M1 is less than the refractive index n of the jacket M1. M1 .

[0908] The optical guide preferably has one, two, three, four, or more than four other sleeves surrounding the core and enclosed by a sleeve M1 (i.e., located between the core and sleeve M1). More preferably, the refractive index of the other sleeves located between the core and sleeve M1 is greater than the refractive index n of sleeve M1. M1 .

[0909] The refractive index of the core of the optical guide preferably decreases towards the outermost jacket. The refractive index can decrease gradually or steadily from the core to the outermost jacket. The refractive index can decrease in different sections. More preferably, the refractive index can decrease gradually in at least one section and steadily decrease in at least one other section. The steps can have the same or different heights. Of course, it is possible to include sections with decreasing refractive index between sections with increasing refractive index.

[0910] Different refractive indices of different jackets can be set by doping jacket M1, other jackets and / or core.

[0911] The core may already have a first jacket layer M0 during manufacturing, depending on how the core is manufactured. This jacket layer immediately adjacent to the core is sometimes referred to as the integral jacket layer. Jacket layer M0 is closer to the center point of the core than jacket M1 and other jackets (if any). Jacket layer M0 is generally not used for conducting light and / or radiation; instead, jacket layer M0 helps ensure that radiation is retained in the core and transmitted there, so that radiation conducted in the core is preferably reflected at the transition from the core to jacket layer M0. This transition from the core to jacket layer M0 is preferably characterized by a change in refractive index. The refractive index of jacket layer M0 is preferably lower than the refractive index n of the core. K The jacket layer M0 preferably contains the same material as the core, but has a lower refractive index than the core by imparting or including additives.

[0912] Preferably, at least the jacket M1 comprises silicon dioxide, and preferably has one or more of the following characteristics:

[0913] a) OH content less than 5 ppm, with a particular preference for less than 1 ppm;

[0914] b) Chlorine content less than 200 ppm, preferably less than 100 ppm, for example less than 80 ppm, and particularly preferably less than 60 ppm;

[0915] c) The aluminum content is less than 200 ppb, preferably less than 100 ppb, for example less than 80 ppb, and particularly preferably less than 60 ppb;

[0916] d) Less than 5.10 15 / cm 3 For example, in 0.1·10 15 up to 3.10 15 / cm 3 Within the range, it is particularly preferred to be within 0.5·10. 15 Up to 2.0.10 15 / cm 3 ODC components within the range;

[0917] e) The metal content of metals other than aluminum is less than 1 ppm, for example less than 0.5 ppm, and particularly preferably less than 0.1 ppm;

[0918] f) in log 10 (η(1250℃) / dPas)=11.4 to log 10 (η(1250℃) / dPas)=12.9 and / or log 10 (η(1300℃) / dPas)=11.1 to log 10 (η(1300℃) / dPas)=12.2 and / or log 10 (η(1350℃) / dPas)=10.5 to log 10 Viscosity in the range of (η(1350℃) / dPas)=11.5 (p=1013hPa);

[0919] g) Curling parameters greater than 6m;

[0920] h) less than 1.10 -4 The uniformity of refractive index;

[0921] i) The transition point Tg is preferably in the range of 1150°C to 1250°C, and particularly preferably in the range of 1180°C to 1220°C.

[0922] The ppb and ppm values ​​are based on the total weight of the jacket M1 in each case.

[0923] The jacket preferably has a density of less than 1.10. -4 Refractive index uniformity. Refractive index uniformity refers to the maximum variation in refractive index at each point in a sample (e.g., jacket M1 or quartz gas), based on the average of all refractive indices measured across all samples in the sample. The average is calculated using the refractive indices from at least seven measurement points.

[0924] The jacket M1 preferably has a metal content of less than 1000 ppb, for example less than 500 ppb, and particularly preferably less than 100 ppb, of metals other than aluminum, based on the total weight of the jacket M1 in each case. However, the jacket M1 typically has a metal content of at least 1 ppb of metals other than aluminum. Such metals include, for example, sodium, lithium, potassium, magnesium, calcium, strontium, germanium, copper, molybdenum, titanium, iron, and chromium. These metals may exist, for example, in elemental form, in ionic form, or as molecules or ions or portions of complexes.

[0925] Jacket M1 may contain other components. Jacket M1 preferably contains less than 5 ppm, for example less than 4.5 ppm, and particularly preferably less than 4 ppm, of other components based on the total weight of jacket M1 in each case. Other elements may include, for example, carbon, fluorine, iodine, bromine, and phosphorus. These elements may be present, for example, in elemental form, in ionic form, or as molecules, ions, or portions of complexes; however, jacket M1 typically has an content of at least 1 ppb of atoms other than Si, O, H, C, and Cl.

[0926] The jacket M1 preferably has a carbon content of less than 5 ppm, for example less than 4 ppm or less than 3 ppm, and particularly preferably less than 2 ppm, based on the total weight of the jacket M1 in each case, but the jacket M1 typically contains at least 1 ppb of carbon.

[0927] In each case, the jacket M1 preferably contains a uniformly distributed amount of OH, Cl and / or Al.

[0928] In one embodiment of the optical guide, the jacket M1 has a weight composition of at least 80% by weight, for example at least 85% by weight, and particularly preferably at least 90% by weight, based on the total weight of the jacket M1 and the core in each case. The jacket M1 preferably has a weight composition of at least 80% by weight, for example at least 85% by weight, and particularly preferably at least 90% by weight, based on the total weight of the jacket M1, the core, and other jackets located between the jacket M1 and the core. The jacket M1 preferably has a weight composition of at least 80% by weight, for example at least 85% by weight, and particularly preferably at least 90% by weight, based on the total weight of the optical guide in each case.

[0929] The jacket M1 preferably has a strength of 2.1 g / cm³. 3 Up to 2.3 g / cm 3 Within the range, it is particularly preferred to be 2.18 g / cm³. 3 Up to 2.22 g / cm 3 Density within the range.

[0930] On the other hand, it relates to an optical guide that can be obtained through a method including the following steps:

[0931] A / Provides a quartz glass body according to a third purpose of the invention, or a quartz glass body that can be obtained by a method according to a first purpose, wherein the quartz glass body is first processed into a hollow body having at least one opening;

[0932] B / Insert one or more mandrels into the quartz glass body through at least one opening to obtain a precursor;

[0933] C / Stretch the precursor from step B / during heating to obtain an optical guide having one or more cores and a jacket M1.

[0934] The features of steps A / , B / and C / are preferably those described in the fourth objective.

[0935] The preferred features of the optical guide are those described in the context of a third purpose.

[0936] A fourth object of the present invention relates to a method for manufacturing an irradiation body, the method comprising the following steps:

[0937] (i) Provide a quartz glass body according to the second purpose of the invention, or a quartz glass body obtained by means of the first purpose, particularly by performing process steps i.) to vii.) according to the first purpose, wherein the quartz glass body is first processed to obtain a hollow body;

[0938] (ii) Optionally assemble the hollow body with the electrodes;

[0939] (iii) Fill the hollow body with gas.

[0940] Step (i)

[0941] In step (i), a quartz glass body is provided. The quartz glass body provided in step (i) is first processed to obtain a hollow body containing at least one opening, such as one opening, two openings, three openings, or four openings, particularly preferably one or two openings.

[0942] The quartz glass obtained by the method according to the first objective is preferably provided for step (i). The quartz glass preferably has the features described in the process of the first objective or the second objective.

[0943] For processing quartz glass for a fourth purpose, more than one option can be considered.

[0944] In principle, a quartz glass body can be processed into a hollow body with an opening using any and all methods known to a person skilled in the art suitable for manufacturing a hollow glass body with an opening. Suitable methods include, for example, those methods including pressing, blowing, suction, or combinations thereof. A hollow body with an opening can also be formed by closing the opening, for example by fusing them together.

[0945] The hollow body contains a material containing silica, the amount of which is preferably in the range of 98% to 100% by weight, for example in the range of 99.9% to 100% by weight, particularly preferably up to 100% by weight, in each case based on the total weight of the hollow body.

[0946] The material used to manufacture the hollow body preferably has at least one, more than one, two, or all of the following characteristics:

[0947] HK1. Based on the total weight of the material, the silica content is preferably greater than 95% by weight, for example greater than 97% by weight, and particularly preferably greater than 99% by weight;

[0948] HK2. at 2.1 g / cm³ 3 Up to 2.3 g / cm 3 Within the range, it is particularly preferred to be 2.18 g / cm³. 3 Up to 2.22 g / cm 3 Density within the range;

[0949] HK3. Based on the amount of light generated within the hollow body, the translucency is in the range of 10% to 100%, for example, in the range of 30% to 99.99%, particularly preferably in the range of 50% to 99.9%, at at least one wavelength in the visible light range of 350 nm to 750 nm.

[0950] HK4. OH content less than 500 ppm, for example less than 400 ppm, and particularly preferably less than 300 ppm;

[0951] HK5. Chlorine content less than 200 ppm, preferably less than 100 ppm, for example less than 80 ppm, and particularly preferably less than 60 ppm;

[0952] HK6. Aluminum content less than 200 ppb, for example less than 100 ppb, and particularly preferred to be less than 80 ppb;

[0953] HK7. Carbon content less than 5 ppm, for example less than 4.5 ppm, and particularly preferred to be less than 4 ppm;

[0954] HK8. Less than 5.10 19 / cm 3 ODC components;

[0955] HK9. The content of metals other than aluminum is less than 1 ppm, for example less than 0.5 ppm, and particularly preferably less than 0.1 ppm.

[0956] HK10. In log 10 η(1250℃)=11.4 to log10 η(1250℃)=12.4 and / or log 10 η(1300℃)=11.1 to log 10 η(1350℃)=11.7 and / or log 10 η(1350℃)=10.5 to log 10 Viscosity within the range of η(1350℃) = 11.1 (p = 1013 hPa);

[0957] HK11. The transition point Tg is particularly preferred in the range of 1150°C to 1250°C, and especially in the range of 1180°C to 1220°C.

[0958] The ppm and ppb values ​​are based on the total weight of the hollow body in each case.

[0959] Step (ii)

[0960] Before filling with gas, the hollow body from step (i) is assembled with electrodes, preferably two electrodes. The electrodes are preferably connected to a power source. The electrodes are preferably connected to a lamp post.

[0961] Electrode materials are preferably selected from the group consisting of metals. In principle, any metal that has not been oxidized, corroded, melted, or whose form or conductivity is not otherwise affected when used as an electrode can be selected as the electrode material. Electrode materials are preferably selected from the group consisting of: iron, molybdenum, copper, tungsten, rhenium, gold, and platinum, or at least two of them, wherein tungsten, molybdenum, or rhenium is preferred.

[0962] Step (iii)

[0963] The hollow body provided in step (i) and, if necessary, assembled with the electrode in step (ii) is filled with gas.

[0964] Filling can be carried out by any and all methods known to those skilled in the art suitable for filling. Gas is preferably fed into the hollow body through at least one opening.

[0965] The hollow body is preferably evacuated before being filled with gas, preferably to a pressure of less than 2 mbar. Then, gas is injected to fill the hollow body. These steps can be repeated to reduce air pollution, particularly oxygen pollution. These steps are preferably repeated at least two, for example at least three or four times, and particularly preferably at least five times, until other gaseous pollutants, such as air, are sufficiently low. This method is particularly preferred for filling hollow bodies with an opening.

[0966] If the hollow body has two or more openings, it is preferably filled through one of those openings. Air in the hollow body can escape through at least one other opening before it is filled with gas. The gas passes through the hollow body until it is contaminated by other gases, particularly oxygen, to a sufficiently low level.

[0967] The hollow body is preferably filled with an inert gas, or a combination of two or more inert gases, such as nitrogen, helium, neon, argon, krypton, xenon, or a combination of two or more thereof, with krypton, xenon, or a combination of nitrogen and argon being particularly preferred. Further preferred fillers for the hollow body used in irradiation are deuterium and mercury.

[0968] Preferably, the hollow body is immediately gas-sealed after filling so that the gas does not escape during further processing, thus preventing air from seeping in from the outside during further processing, or both. Sealing can be accomplished by melting or bonding a sealant. Suitable sealants are, for example, quartz glass sealants, which are fused to the hollow body or lamp post. The hollow body is preferably sealed by melting.

[0969] The irradiating body comprises a hollow body and, if necessary, electrodes. The irradiating body preferably has at least one, for example, at least two, at least three, or at least four, and particularly at least five, of the following characteristics:

[0970] I.) at 0.1cm 3 Up to 10m 3 Within a range, for example, within 0.3cm 3 up to 8m 3 Within the range, it is particularly preferred to be within 0.5cm. 3 up to 5m 3 Volume within the range;

[0971] II.) The length is in the range of 1 mm to 100 m, for example, in the range of 3 mm to 80 m, and particularly preferably in the range of 5 mm to 50 m;

[0972] III.) The emission angle is in the range of 2° to 360°, for example, in the range of 10° to 360°, and particularly preferably in the range of 30° to 360°;

[0973] IV.) Light emission in the wavelength range of 145 nm to 4000 nm, for example in the range of 150 nm to 450 nm or 800 nm to 4000 nm, particularly preferably in the range of 160 nm to 280 nm;

[0974] V.) in the range of 1mW to 100kW, particularly preferably in the range of 1kW to 100kW, or in the range of 1 watt to 100 watts.

[0975] On the other hand, it relates to the irradiated body that can be obtained through a method including the following steps:

[0976] (i) To prepare a quartz glass body according to the second purpose of the invention, or a quartz glass body that can be obtained according to the first purpose, in particular by performing process steps i.) to vii.), wherein the quartz glass body is first processed into a hollow body;

[0977] (ii) Optionally assemble the hollow body with the electrodes;

[0978] (iii) Fill the hollow body with gas.

[0979] The features of steps (i), (ii) and (iii) are preferably those described in the seventh objective process.

[0980] The preferred features of the irradiated body are those described in the seventh objective process.

[0981] A fifth object of the present invention relates to a method for manufacturing a molded article, the method comprising the following steps:

[0982] (1) To provide a quartz glass body according to the second purpose of the invention, or a quartz glass body that can be obtained according to the first purpose, in particular by performing process steps i.) to vii.) according to the first purpose;

[0983] (2) Shape the quartz glass body to obtain a molded body.

[0984] The quartz glass provided in step 1) is a quartz glass obtained according to the second purpose or by a method according to the first purpose of the invention. The provided quartz glass preferably has the characteristics of the first or second purpose.

[0985] Step (2)

[0986] To form the quartz glass body provided in step (1), any and all methods known to those skilled in the art and suitable for forming quartz glass may be considered. As described in the processes of the first, fourth, and fifth objectives, the quartz glass body is preferably manufactured into a molded body. The molded body may also preferably be formed by methods known to glass blowrs.

[0987] The molded body can, in principle, take any form that can be molded from quartz glass. Preferred molded bodies include, for example:

[0988] - A hollow body with at least one opening, such as a circular piston and a vertical piston.

[0989] - Attachments and closures for such hollow bodies

[0990] - Open-architecture products, such as shells and boats (or wafer carriers),

[0991] - Crucible with open and lockable design

[0992] - Metal sheets and windows,

[0993] -Colorimetric tubes

[0994] - Tubes and hollow cylinders, such as reaction tubes, profiled tubes, rectangular chambers,

[0995] -For example, rods, bars, and blocks with circular or angular, symmetrical or asymmetrical designs.

[0996] - Tubes and hollow cylinders sealed on one or both sides,

[0997] - Dome and bell-shaped components,

[0998] -Flange,

[0999] - Lenses and prisms

[1000] - Welded components,

[1001] - Bending components, such as convex or concave surfaces and sheets of metal, bent bars and tubes.

[1002] According to one implementation scheme, the molded body can be processed after molding. Here, in principle, all methods suitable for finishing quartz glass described in the first objective process can be considered. The molded body can preferably be machined, for example, by drilling, honing, external grinding, splitting, or elongation.

[1003] On the other hand, it relates to molded bodies that can be obtained by a method comprising the following steps:

[1004] (1) Provide a quartz glass body according to the second purpose of the invention, or a quartz glass body that can be obtained by the method according to the first purpose of the invention, in particular by performing process steps i.) to vii.) according to the first purpose;

[1005] (2) Shape the quartz glass body to obtain a molded body.

[1006] The features of steps (1) and (2) are preferably those described in the eighth objective process.

[1007] The preferred features of the molded body are those described in the eighth objective process.

[1008] A sixth objective of the present invention is a method for preparing a coating on a substrate, the method comprising the following steps:

[1009] |A| Provides a silica suspension and a substrate that are available according to the first objective or one of its embodiments;

[1010] |B| Apply a coating of silica suspension to a substrate;

[1011] A coating is formed on the substrate.

[1012] The silica suspension provided in step |A| can be obtained by a method according to the first objective of the present invention. The silica suspension may have other features corresponding to the embodiments described in conjunction with the first objective.

[1013] The application in step |B| can be carried out in principle by any method suitable for preparing the coating, coating at least part of the substrate with a silica suspension.

[1014] In another embodiment, application can be performed by depositing a silica suspension onto a substrate, immersing the substrate in a silica suspension, or a combination of both. Application by depositing a silica suspension can be carried out, for example, by spin coating, saturation, casting, dripping, injection, spraying, raking, coating, or printing, such as via metering pumps or inkjet printing, screen printing, gravure printing, offset printing, or buffer printing onto the substrate. The silica suspension can be applied to achieve a wet film thickness in the range of 0.01 μm to 250 μm, for example, in the range of 0.1 μm to 50 μm.

[1015] Deposition further refers to the application of a silica suspension to a substrate by a means. This can be done through various means. Thus, the silica suspension applied to the substrate can be sprayed from a nozzle, injected, or deposited through a slit nozzle. Other suitable methods include curtain casting and spin coating. The silica suspension can also be applied to the surface of the substrate, for example, via rollers or drums. Known spraying and / or injection methods include, for example, micro-dispensing via nozzles or digital printing. This can be done using a silica suspension for deposition or simply dripping the silica suspension onto the substrate.

[1016] In the case of immersion, the substrate can be removed from the silica suspension bath. If only a portion of the substrate is to be coated, only the surface to be coated can be immersed in the silica suspension and removed again as needed, as performed, for example, by dip coating. Different coating thicknesses can be achieved using repeated immersion. The coating thickness can also be set by the viscosity and solids composition of the silica suspension. By application, a wet layer thickness of silica suspension in this manner can be achieved in the range of 0.5 μm to 1000 μm, preferably in the range of 5 μm to 250 μm, and particularly preferably in the range of 10 μm to 100 μm.

[1017] Subsequently, the liquid component of the coating may be reduced, depending on the circumstances but not necessarily for step [C]. Step |C| is performed until the liquid component of the coating, based on the total weight of the coating, reaches or decreases below a set point. This set point may be, for example, 10 wt%, 5 wt%, 2 wt%, or also 0.2 wt%, which in each case is based on the total weight of the coating. In principle, any and all methods known to those skilled in the art that appear suitable for reducing the liquid component of the layer may be considered, particularly at least one method selected from the group consisting of: heat drying; drying by covering the coating with a gas or gas mixture; evaporating the liquid at reduced ambient pressure; exciting the liquid, for example, by using microwaves to excite molecular motion in the case of water, etc. Combinations of two or more of the methods may also be considered, wherein the combination may be designed to be simultaneous, continuous, or overlapping in space and / or time. In this context, overlapping means that one method may even begin before the previous method is completed.

[1018] The invention will now be described with the aid of accompanying drawings. These drawings are not to scale and are not intended to limit the scope of the invention.

[1019] Brief description of the attached figures

[1020] Attached Figure

[1021] Figure 1 Flowchart (Method for manufacturing quartz glass)

[1022] Figure 2 Flowchart Variation (Method for Manufacturing Quartz Glass)

[1023] Figure 3 First filter arrangement with three filtration stages (first filtration stage, second filtration stage, and third filtration stage)

[1024] Figure 4 Schematic diagram of a spray tower

[1025] Figure 5 Schematic diagram of a suspended crucible in a furnace.

[1026] Figure 6 Schematic diagram of a vertical crucible in a furnace.

[1027] Figure 7 Schematic diagram of a crucible with a dew point measuring device

[1028] Figure 8 Flowchart (Method for Manufacturing Molded Objects)

[1029] Figure 9 provides an exemplary representation: a) particle size distribution in the slurry prior to step iii.), and b) the precursor suspension after dispersion in step iii.).

[1030] Figure 10 Examples of hot-dip quartz glass: a) many bubbles, b) few bubbles, c) very many bubbles (foam glass)

[1031] Figure 11 Comparison of tungsten contaminants in quartz glass samples: a), b) hot glass, a) severely contaminated with tungsten, b) no tungsten contaminants, c) tungsten discoloration on frozen double glass tubes.

[1032] Figure 12 Comparative images of frozen quartz glass samples, wherein the melt is formed from particles and is made from: a) an unfiltered silica suspension; b) a filtered silica suspension as described in this invention.

[1033] Figure 13 Simplified diagram of the setup for evaluating the fluorescence of quartz glass samples Attached Figure Description

[1034] Figure 1 A flowchart is shown illustrating steps 101 to 107 of a method 100 for manufacturing a quartz glass body according to the present invention, the method comprising at least the following steps: (i) providing a powder of silica particles and a liquid 101; (ii) providing a slurry by mixing the powder and the liquid; (iii) treating the slurry with ultrasound to obtain a precursor suspension 103; (iv) passing at least a portion of the precursor suspension through a first multi-stage filtration device, wherein a silica suspension (104) is obtained; v.) forming silica particles from the silica suspension; vi.) forming a glass melt from the silica particles in a furnace; vii.) forming a quartz glass body from at least a portion of the glass melt.

[1035] In step iii.), processing the slurry involves crushing at least a portion of the silica particles to obtain a so-called precursor suspension. The first multi-stage filtration device in step iv.) is designed such that it has at least a first filtration stage, a second filtration stage, and a third filtration stage, wherein the second filtration stage is downstream of the first filtration stage and the third filtration stage is downstream of the second filtration stage. Each filtration stage includes at least one filter. Step v.) includes granulation, wherein the particle size of the silica particles is larger than the particle size of the silica particles contained within the silica particles. Figure 1 In the method described herein, a silicon component other than silicon dioxide (not shown) is added in at least one of the process steps.

[1036] A furnace includes a melting furnace. This can be designed as either a suspended or vertical melting furnace (see [link]). Figure 5 and Figure 6The furnace and / or melting crucible also have at least one gas outlet, but usually also a gas inlet, which can affect the atmosphere present in the furnace. For a detailed explanation of this, particularly the method for measuring the dew point of the gas as it exits the furnace, see [link to relevant documentation]. Figure 5 , Figure 6 and Figure 7 .

[1037] The melting in step 106 is preferably carried out in a reducing hydrogenation atmosphere. In step 107, a quartz glass body is formed. Here, the quartz glass body is preferably formed by removing at least a portion of the molten glass from the crucible and cooling it. It can be removed via a nozzle at the lower end of the crucible. In this case, the form of the quartz glass body can be determined by the design of the nozzle. For example, a solid body can be obtained. For example, if a mandrel is also provided in the nozzle, a hollow body is obtained. This method for manufacturing a quartz glass body, as illustrated by way of example, and particularly step 107, is preferably carried out continuously. Alternatively to step 107, a solid quartz glass body can be formed in an optional downstream step 108.

[1038] Figure 2 Showing with Figure 1 The same method applies. Silicon component 210, other than silicon dioxide, is added during steps i.) 201, ii.) 202, or v.) 205, preferably before particle formation in the latter case. Silicon component 210 may also be added during two steps or during all three steps (i.e., in more than one portion).

[1039] Figure 3 A schematic filter arrangement comprising three filtration stages is shown, each stage having a first filter 301, a second filter 302, and a third filter 303. These filtration stages are arranged downstream.

[1040] Figure 4A preferred embodiment of a spray tower 1100 for spray granulation of silica is shown. The spray tower 1100 includes a feed section 1101 through which a pressurized slurry containing silica powder and liquid is fed into the spray tower. At the end of the line is a nozzle 1102 through which the slurry is fed into the spray tower in a finely distributed manner. The nozzle is preferably angled upwards, such that the slurry is sprayed into the spray tower as fine droplets along the direction of the nozzle arrangement and then falls in a curved path under gravity. At the upper end of the spray tower is a gas inlet 1103. Gas is injected through the gas inlet 1103 to generate an airflow in the opposite direction to the slurry exiting from the nozzle 1102. The spray tower 1100 also includes a screening device 1104 and a sieving device 1105. Particles smaller than a defined particle size are drawn away by the screening device 1104 and removed via the outlet 1106. The suction intensity of the screening device 1104 can be adjusted according to the particle size of the particles to be drawn away. The sieving device 1105 filters out particles larger than a predetermined particle size, which are removed through outlet 1107. The sieve permeability of the sieving device 1105 can be selected according to the particle size of the particles to be removed. The remaining particles (silica particles of the desired size) are removed through outlet 1108.

[1041] Figure 5 A preferred embodiment of a furnace 800 with a suspended crucible is shown. The crucible 801 is suspended within the furnace 800. The crucible 801 has a suspension 802 in its upper region and a solid inlet 803 and a nozzle 804 as an outlet. The crucible 801 is filled with silica particles 805 via the solid inlet 803. In operation, the silica particles 805 are present in the upper region of the crucible 801, while the molten glass 806 is present in the lower region of the crucible 801. The crucible 801 can be heated by a heating element 807 arranged on the exterior of the crucible wall 810. The furnace also has an insulating layer 809 between the heating element 807 and the furnace outer wall 808. The space between the insulating layer 809 and the crucible wall 810 can be filled with gas, for which it has a gas inlet 811 and a gas outlet 812. The quartz glass 813 can be removed from the furnace via the nozzle 804.

[1042] Figure 6A preferred embodiment of a furnace 900 with a vertical crucible is shown. The crucible 901 is vertically arranged within the furnace 900. The crucible 901 has a vertical surface 902, a solid inlet 903, and a nozzle 904 as an outlet. The crucible 901 is filled with silica particles 905 via the inlet 903. In operation, the silica particles 905 are present in the upper region of the crucible 901, while the molten glass 906 is present in the lower region of the crucible 901. The crucible 901 can be heated by a heating element 907 arranged on the exterior of the crucible wall 910. The furnace also has an insulating layer 909 between the heating element 907 and the furnace outer wall 908. The space between the insulating layer 909 and the crucible wall 910 can be filled with gas, for which it has a gas inlet 911 and a gas outlet 912. The quartz glass 913 can be removed from the crucible 901 via the nozzle 904.

[1043] Figure 7 A melting crucible 1400 is shown. The crucible has a solid inlet 1401 and an outlet 1402. In operation, silica particles 1403 are located in the upper region of the crucible 1400 in the form of a stationary cone, while molten glass 1405 is present in the lower region of the crucible. The crucible 1400 has a gas inlet 1406 and a gas outlet 1407. The gas inlet 1406 and the gas outlet 1407 are arranged above the stationary cone 1404 of silica particles 1403. The gas outlet 1407 includes a gas line 1408 and a device 1409 for measuring the dew point of the discharged gas. The device 1409 includes, for example, a dew point level hygrometer (not shown here). The distance between the crucible and the device 1409 for measuring the dew point can vary. Quartz glass 1410 can be removed via the outlet 1402 of the crucible 1400.

[1044] Figure 8 A flowchart illustrating steps 401 and 402 of a method for manufacturing a molded article is shown. In the first step 401, a quartz glass body is provided, preferably as shown in the flowchart. Figure 1 The quartz glass body shown is manufactured as illustrated. This type of quartz glass body can be a solid quartz glass body or a hollow quartz glass body. In the second step 402, a molded body is formed from the solid quartz glass body provided in step 401.

[1045] Figure 9. Graph a) illustrates, by way of example, the particle size distribution of a silica powder slurry in water on which the method of the present invention is based. This graph shows the amount of fully slurried silica particles with a particle size less than 1 μm, and also shows a series of agglomerates in the ranges of 1 μm to 5 μm and 10 μm to 100 μm. Graph b) shows the particle size distribution of a silica suspension obtained by dispersing the silica slurry as in Figure a). Now, all particles are dispersed. Silica particles with a particle size greater than 1 μm are not shown. Through subsequent filtration, from... Figure 5b) The particle size distribution of silica particles is maintained; however, particles other than silica are separated.

[1046] Figure 10 The following comparative images are shown: (hot) glass bodies approximately 1 m after removal from the melting furnace, wherein a) a melt formed from an unfiltered silica suspension; b) a glass body wherein the melt used is particles of a filtered silica suspension according to the invention; and c) a glass body wherein the melt used is particles as in Examples 15-4, that is, the pyrolytic silica suspension was treated with a ball mill (zirconia balls and a polyurethane-coated cup) before filtration.

[1047] Figure 11 Comparative images of glass containing tungsten contaminants are shown. Images a) and b) show the hot glass approximately 1 m after being removed from the molten crucible. Image a) shows the glass contaminated with tungsten, streaks, and discoloration. Image b) shows the glass without tungsten contamination, etc. Image c) shows two cooled double glass tubes as an example. The left glass tube is transparent but darker. The hue is based on relatively uniform tungsten contamination. The right glass tube is free of such contaminants. It is transparent and non-absorbent in the visible light range.

[1048] Figure 12 Two different cooled quartz glass bodies are shown. The quartz glass body in image a) is made from a suspension of silica particles not treated according to the present invention. It contains a large number of large bubbles. The quartz glass body in image b) is made based on a silica suspension treated according to the present invention. Almost no bubbles are visible.

[1049] Figure 13 A sketch of the setup for measuring the fluorescence of a quartz glass sample is shown. In a darkroom, sample 1301 is illuminated with UV light from UV lamp 1303 at a 90° angle (a) to the observer's line of sight 1302 against a black background. The distance from the UV lamp to the sample is less than 1 cm. The sample has a length of 10 mm in the direction of UV light propagation.

[1050] Test methods

[1051] a. OH content

[1052] The OH content of the glass was determined by infrared spectroscopy using the method described by DMDodd and DMFraser, "Optical Determinations of OH in Fused Silica" (JAP37, 3991 (1966)). Instead of the apparatus described above, an FTIR (Fourier Transform Infrared) spectrometer (currently the Perkin Elmer System 2000) was used. In principle, the OH content at approximately 3670 cm⁻¹ can be measured. -1 The absorption band at approximately 7200 cm⁻¹ -1 The absorption bands at the OH sites were analyzed in the spectrum. The bands used were selected based on the rule that the transmittance loss due to OH absorption is between 10% and 90%.

[1053] b. Oxygen-deprived centers (ODCs)

[1054] As a quantitative demonstration, the ODC(I) absorption was determined at 165 nm by measuring the transmittance of a 1 mm–2 mm thick sample using a McPherson, Inc. (USA) VUVAS 2000 vacuum UV spectrometer.

[1055] but:

[1056] N=α / σ

[1057] in

[1058] N = Defect concentration [1 / cm3]

[1059] Optical absorption of the ODC (I) band α [1 / cm, base e]

[1060] σ = Effective cross-sectional area [cm] 2 ]

[1061] The effective cross-sectional area used is σ = 7.5·l0. -17 cm 2 (From L. Skuja, "Color Centers and Their Transformations in Glassy SiO2", Lectures of the summer school "Photosensitivity in optical waveguides and glasses", Vitznau, Switzerland, July 13-18, 1998).

[1062] c. Elemental analysis

[1063] c-1) Crush the solid sample; then place approximately 20g of the sample into an HF-resistant container, completely cover it with HF, and heat-treat at 100°C for one hour. After cooling, immediately discard the acid and wash the sample several times with the purest water. Then dry the container with a probe in a drying oven.

[1064] Add approximately 2 g of solid sample (such as the cleaned fragmented material; dust, etc., not directly pretreated) and 15 ml of HF (50% by weight) to a HF-resistant lock container. Lock the container and heat-treat at 100°C until the solid sample is completely dissolved. Then open the lock container and heat-treat further at 100°C until the solution is completely evaporated. Meanwhile, fill the lock container with 3 × 15 ml of ultrapure water. Add 1 ml of HNO3 to the lock container to dissolve the separated contaminants, and fill with ultrapure water to 15 ml. The test solution is now ready.

[1065] c-2) Measurement of ICP-MS / ICP-OES

[1066] Whether to use OES or MS depends on the expected elemental concentration. Typical MS decision thresholds are approximately 1 ppb for MS and approximately 10 ppb for OES (based on the weight of the sample in each case). This varies slightly for each element. Elemental concentrations are determined using the testing equipment according to the equipment manufacturer's instructions (ICP-MS: Agilent 7500ce; ICP-OES: Perkin Elmer 7300DV), using a certified calibration reference fluid. The elemental concentration in the solution (15 ml) determined by the equipment is then extrapolated for the weight of the sample used (2 g).

[1067] NB: Please note that the acid, container, water, and equipment must be sufficiently pure to determine the proven elemental concentration. This is then rechecked by connecting a blind sample without quartz glass.

[1068] The elements determined by this method are as follows: Li, Na, Mg, K, Ca, Fe, Ni, Cr, Hf, Zr, Ti, V, Nb, W, Mo, and Al.

[1069] c-3) As described above, measure the liquid sample, but instead of preparing the sample as in step c-1), place 15 ml of the liquid sample into a locked container, without extrapolating from the initial weighed amount.

[1070] The precise decision thresholds for ICP-MS and / or ICP-MS, depending on the element being analyzed, are shown in the table below:

[1071] Element / Ion Determination threshold: ICP-OES [ppb] Determination threshold: ICP-MS [ppb] Li 10 0.5 Na 20 5 Mg 10 3 K 20 5 Ca 30 15 Fe 10 5 Ni 8 1 Co 10 1 Cr 8 1 Cu 8 1 Ge 100 2 Hf 10 Mn 8 1 Zn 20 5 Zr 10 3 Ti 10 2 V 10 0.5 Nb 10 W 10 5 Mo 10 1 Al 40 10

[1072] d. Determining the density of a liquid

[1073] Liquid density is determined by weighing a precisely defined volume of liquid into a test container that is inert to the liquid and its components, wherein the empty weight and the weight of the filled container are measured. The density is obtained by dividing the difference between the two weight measurements by the volume of liquid weighed.

[1074] e. Evidence proving fluoride ions

[1075] Crush 15g of quartz glass sample and clean it by treating it in nitric acid at 70°C; then rinse the sample several times with ultrapure water and dry it. Weigh 2g of the sample into a nickel crucible and cover it with 10g Na₂CO₃ and 0.5g ZnO. Cover the crucible with a Ni cap and anneal at 1000°C for one hour; then fill the nickel crucible with water and boil it until the melt cake is completely dissolved. Transfer the solution to a 200ml test tube and fill it to 200ml with the cleanest water. After separating the undissolved components, take 30ml and transfer it to a 100ml test tube, add 0.75ml acetic acid and 60ml TISAB, and fill it to 200ml with the purest water. Transfer the test solution to a 150ml glass beaker.

[1076] Connected to Wissenschaftlich-Technische via an ion-sensitive (fluoride ion) electrode and a display unit (in this case, a fluoride ion selective electrode and a reference electrode F-500 with R503 / D) suitable for the expected concentration range. Using the pMX 3000 / pH / ION from GmbH, the fluoride ion content of the test solution was determined according to the manufacturer's instructions. The fluoride ion concentration in the quartz glass was calculated from the fluoride ion concentration in the solution, the dilution factor, and the weight.

[1077] f. Evidence proving chlorine (≥60ppm)

[1078] Crush 15g of glass sample and clean it by treating it in nitric acid at approximately 70°C; then rinse the sample several times with the purest water and dry it. Place 2g of the sample into a PTFE insert in a pressure vessel, add 15ml of NaOH (c = 10mol / L), seal with a PTFE cap, and place in the pressure vessel. Seal and treat at approximately 155°C for 24 hours. After cooling, remove the PTFE insert and transfer the solution completely to a 100ml test tube. Here, add 10ml of HNO3 (65% by weight) and 15ml of acetate buffer, cool, and fill to 100ml with the purest water. Transfer the test solution to a 150ml glass beaker. The test solution should have a pH value between 5 and 7.

[1079] Connect to the Wissenschaftlich-Technische using an ion-sensitive (chloride ion) electrode and a display device (in this case, a Cl-500 type electrode and an R-503 / D type reference electrode) suitable for the expected concentration range. GmbH's pMX 3000 / pH / ION, according to the manufacturer's instructions, determines the chloride ion content of the test solution.

[1080] g. Chlorine content (<60ppm)

[1081] The chlorine content in quartz glass, ranging from <60 ppm to 0.1 ppm, was determined by neutron activation analysis (NAA). For this purpose, three boreholes, each 3 mm in diameter and 1 cm in length, were drilled. These boreholes were sent to the research institution for analysis, in this case, to the Institute of Nuclear Chemistry at Johannes-Gutenberg-University in Mainz. To remove chlorine contamination from the samples, it was agreed that the research institution would thoroughly clean the samples on-site and only immediately before measurement in an HF bath. Each borehole was measured several times. The results and boreholes were then returned to the research institution.

[1082] h. Optical features

[1083] The transmittance of the quartz glass samples was determined using a Perkin Elmer commercial matrix spectrometer or FTIR spectrometer (Lambda 900 [190 nm–3000 nm] or System 2000 [1000 nm–5000 nm]). The required test range guides this section.

[1084] To determine absolute transmittance, the sample body was polished on a parallel plane (surface roughness RMS < 0.5 nm), and once all residues had been removed by polishing, all surface residues were removed by ultrasonic treatment. The sample thickness was 1 cm. In cases where strong transmittance loss is expected due to contamination, additives, etc., thicker or thinner samples must be selected to keep them within the testing range of the equipment. As the sample thickness, a sample thickness (measurement length) was selected at which radiation appears in the sample with only a small number of artifacts, while the effect is sufficiently detectable.

[1085] To measure opacity, the sample is placed in front of the Ulbricht sphere in the radiation. The opacity is calculated using the transmittance value T measured in this way, according to the following formula: O = 1 / T = I0 / I.

[1086] i. Refractive index and refractive index distribution at the tube or rod

[1087] The refractive index distribution of the tube / rod can be characterized using York Technology Ltd.'s Preform Profiler P102 or P104. For this purpose, the rod is inserted into a measurement chamber and sealed tightly. The measurement chamber is then filled with an oil whose refractive index at the 633 nm test wavelength is very similar to the refractive index passing through the outermost glass layer at 633 nm. A laser beam then passes through the measurement chamber along the radiation direction. A detector is installed behind the measurement chamber (along the radiation direction) and measures the angle of refraction (comparing the radiation entering the measurement chamber to the radiation emanating from it). Assuming the refractive index distribution of the rod is symmetrical, the diameter process of the refractive index can be reconstructed using the inverse Abel transformation. These calculations are performed using software from the equipment manufacturer, York.

[1088] Similar to the description above, the refractive index of the sample was determined using a York Technology Ltd. Preform Profiler P104. Even in the case of isotropic samples, measuring the refractive index distribution yields only one value: the refractive index itself.

[1089] j. Carbon content

[1090] Quantitative determination of surface carbon content in silica particles and silica powder was performed using a Leco Corporation, USA RC612 carbon analyzer. This was achieved by oxidizing all surface carbon contaminants (except SiC) to carbon dioxide using oxygen. For this purpose, 4.0 g of sample was weighed and inserted into the quartz glass plate of the carbon analyzer. The sample was rinsed with pure oxygen and heated at 900°C for 180 seconds. The CO2 formed was recorded using the infrared detector of the carbon analyzer. Under these measurement conditions, the evidence for the detection threshold was ≤1 ppm (wt%) of carbon.

[1091] The quartz glass metal sheet suitable for this analysis in the aforementioned carbon analyzer is available through a laboratory request, and in the case of this invention, from Deslis Laborhandel, Flurstrasse 21, D-40235 Düsseldorf, Germany, Deslis No. LQ-130XL, as a consumable for the LECO analyzer (LECO No. 781-335). This type of sheet has width / length / height dimensions of approximately 25 mm / 60 mm / 15 mm. The quartz glass metal sheet is filled with sample material to half its height. For silica powder, 1.0 g of sample material can be weighed. The lower limit of detection threshold is <1 wt-ppm carbon. Up to 4 g of silica particles (with an average particle size in the range of 50 μm to 500 μm) can be weighed into the same quartz glass metal sheet at...

Claims

1. A method for manufacturing a quartz glass body, the method comprising the following process steps: i.) Provides powdered and liquid silica particles; ii.) By mixing the powder and the liquid to form a slurry containing the liquid and the silica particles; iii.) The slurry is treated with ultrasound to obtain a precursor suspension; iv.) Pass at least a portion of the precursor suspension through a first multi-stage filtration device to obtain a silica suspension; v.) Formation of silica particles from the silica suspension; vi.) Forming a glass melt from the said silica particles in a furnace; vii.) A quartz glass body is formed from at least a portion of the glass melt; The ultrasonic treatment of the slurry in step iii.) includes depolymerizing at least a portion of the silica particles; In at least one of the process steps i.)-vi.), a silicon component other than silicon dioxide is added; Step v.) includes at least granulation; The particle size of the silica particles is larger than the particle size of the silica particles contained in the silica suspension. The furnace described above has a melting crucible and a gas outlet. The gas is taken out from the furnace through the gas outlet; The gas has a dew point below 0°C when it is discharged from the furnace via the gas outlet. The first multi-stage filtration device has at least a first filtration stage, a second filtration stage, and a third filtration stage, wherein the second filtration stage is arranged downstream of the first filtration stage, and the third filtration stage is arranged downstream of the second filtration stage. Each filtration stage includes at least one filter. The first filtration stage has a filtration fineness of 5µm or greater, the second filtration stage has a filtration fineness in the range of 0.5µm to 5µm, and the third filtration stage has a filtration fineness of 1µm or less. The filtration fineness refers to the minimum particle size retained by the filter. The first filtration stage has a separation rate of 50% or higher, the second filtration stage has a separation rate of 95% or higher, and the third filtration stage has a separation rate of 99.5% or higher, wherein the separation rates are determined according to ISO 16889:2008 in each case, and wherein the separation rate is (β) x -1) / β x , where β x Value in N x and N h The quotient is determined, where N x N is the number of particles upstream of the filter. h =Number of particles downstream of the filter; and Where x is the filtration fineness, which is the particle size used to determine the separation rate, in µm.

2. The method according to claim 1, wherein the granulation is selected from the group consisting of: roller granulation, spray granulation, centrifugal atomization, cryogenic granulation, and fluidized bed granulation.

3. The method according to claim 1 or 2, wherein the silicon component other than silicon dioxide is silicon.

4. The method of claim 3, wherein the total amount of silicon components other than silicon dioxide is from 10 ppm to 100,000 ppm, wherein the ppm is related to the total weight of silicon dioxide.

5. The method according to claim 1 or 2, wherein the dew point of the gas before it enters the furnace via the gas inlet is at least 30°C lower than the dew point when it leaves the furnace via the gas outlet.

6. The method according to claim 1 or 2, wherein the melting crucible is at least partially formed of a material comprising one or more metals selected from molybdenum, tungsten, rhenium, iridium, and osmium.

7. The method according to claim 1 or 2, wherein the first multi-stage filtration device is characterized by at least one of the following features: (a) The first filtration stage has a filtration fineness in the range of 5µm to 15µm; (b) The first filtration stage has a separation rate in the range of 50% to 90%; (c) The second filtration stage has a filtration fineness in the range of 0.5µm to 2µm; (d) The second filtration stage has a separation rate of 95% or higher; (e) The third filtration stage has a separation rate in the range of 99.5% or higher.

8. The method according to claim 1 or 2, wherein at least one filter in the first multi-stage filtration device selected from one of the filtration stages selected from the first filtration stage, the second filtration stage, and the third filtration stage is designed as a depth filter.

9. The method according to claim 1 or 2, wherein the slurry is treated with ultrasound for at least 10 seconds.

10. The method according to claim 1 or 2, wherein the ultrasonic treatment of the slurry is characterized by a power density of up to 600 W / L.

11. The method according to claim 1 or 2, wherein the slurry has less than 5% by weight of additives to stabilize the slurry, the percentage by weight being based on the total weight of the slurry.

12. A quartz glass obtained by the method according to any one of claims 1-11, the quartz glass having the following characteristics: A] Chlorine content less than 60 ppm; B] Aluminum content less than 200 ppb; C] Less than 5.10 19 / cm 3 ODC components; D] The content of atoms other than Si, O, H and C is less than 5 ppm; At p = 1013 hPa, the viscosity is in log... 10 (ƞ (1250℃) / dPas) = ​​11.4 to log 10 Within the range of (ƞ (1250℃) / dPas) = ​​12.9; F] less than 10 -4 The refractive index uniformity refers to the maximum variation in refractive index at each point in the sample, based on the average of all refractive indices measured in all samples in the sample. G] Cylindrical shape; Tungsten content [H] less than 100 ppb; I] Molybdenum content less than 100 ppb; The ppb and ppm are, in each case, based on the total weight of the quartz glass.

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