Method for manufacturing a quartz glass firing body and composition for molding it

Abstract

The present invention provides a molding composition and a method for producing a quartz glass firing body using the molding composition, which can produce a sound quartz glass firing body free from internal bubbles, blisters, and cracks. [Solution] A molding composition comprising: quartz glass powder with an average particle size of 0.5 μm or less and 0.05 μm or more that can be fired; an organic binder comprising a thermoplastic resin (A); one or more organic compounds (B) selected from wax, polyethylene glycol, or pluronic surfactants; and a fatty acid compound (C). A method for producing a fired quartz glass body using the molding composition, comprising the steps of: molding the molding composition by injection molding or extrusion molding to obtain a molded body; heating the molded body to degrease it to obtain a degreased molded body; and firing the degreased molded body.

Description

Technical Field

[0001] The present invention relates to a manufacturing method for mass-producing a quartz glass fired body having a complex shape such as a jig for semiconductor manufacturing, an optical component, and a heat insulating material for the semiconductor industry with high purity and high precision.

Background Art

[0002] Conventionally, several methods have been attempted as methods for manufacturing quartz glass products having a complex shape. As a first method, attempts have been made to purify a raw quartz stone, melt it at a high temperature of 2000°C or higher, and directly cast a raw material into a mold to manufacture a quartz glass product having a complex shape. In order to manufacture a thin and complex-shaped quartz glass product by the first method, since the viscosity of molten quartz is high, casting is difficult.

[0003] As a second method, there is a method for manufacturing a quartz glass product by the sol-gel method (Patent Document 1). The second method is a method for manufacturing quartz glass by firing gel fine powder obtained by hydrolyzing a silicate ester or a mixture obtained by adding a metal alkoxide or a metal salt to a silicate ester. In the second method, pre-firing is performed at a low temperature of about 800°C to 1200°C, and then firing is performed at a temperature in the range from 900°C to the glass transition point of quartz glass under hydrostatic pressure to obtain transparent quartz glass. In this method, since quartz glass shrinks greatly during firing of the gel fine powder, there is a problem that cracks and bulges are likely to occur in the manufactured quartz glass product.

[0004] As a third method, a so-called slip casting method has been proposed, in which a slurry consisting of ceramic powder (for example, quartz or glass), water, and a binder is poured into a mold, dried, and then sintered to obtain a molded product. In this case, the problems of the first method described above can be solved by using this slip casting method. However, while the slip casting method is suitable for molding relatively large objects (for example, those with a diameter of 10 mm or more), it is not suitable for small, thin-walled, and complexly shaped parts, and its dimensional accuracy is only about 50 μm, making it unsuitable for optical components that require high dimensional accuracy (Patent Documents 2 and 3). A fourth method for producing silica glass (quartz glass) products involves mixing silica fine powder and a cellulose derivative, injection molding the mixture, followed by degreasing, purification, and firing, characterized in that the cellulose derivative is a cellulose derivative that undergoes reversible thermal gelation in an aqueous solution (Patent Document 4). Cellulose derivatives used in the fourth method tend to produce carbides during thermal decomposition, leading to the formation of bubbles in the silica glass product, and the degreasing process is time-consuming. Furthermore, if water is selected as the binder in the fourth method, it is difficult to stabilize the viscosity, and if the amount of binder is not properly controlled, the dimensions of the product may fluctuate significantly.

[0005] When injection molding and extrusion molding quartz glass, it is necessary to add an organic binder to process it into the desired shape. The organic binder is necessary to impart the shape during molding, and after molding, it is necessary to remove the added organic binder (degrease) by heating or using a solvent. However, in order to produce transparent quartz glass, the particle size of the quartz powder used must be submicron size, and if the organic binder used is not appropriately selected at this time, cracks, voids, and blisters may occur in the quartz glass. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 176931 / 1983 [Patent Document 2] Japanese Patent Publication No. 2000-103630 [Patent Document 3] Japanese Patent Publication No. 2003-270486 [Patent Document 4] Japanese Patent Publication No. 2014-15389 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, the present invention aims to provide a method for producing a quartz glass firing body that can be obtained without the occurrence of blistering or bubbles. [Means for solving the problem]

[0008] One aspect of the present invention is a quartz glass powder with an average particle size of 0.5 μm or less and 0.05 μm or more that can be fired, One or more thermoplastic resins (A) selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, butyl methacrylate resin, polyethylene resin, and polyvinyl butyral resin; (B) One or more waxes selected from paraffin wax or microcrystalline wax, or one or more organic compounds selected from polyethylene glycol or pluronic surfactants; and An organic binder comprising one or more fatty acid compounds (C) selected from fatty acid esters or fatty acid amides, A molding composition comprising the following steps: obtaining a molded article by molding the molding composition, wherein the thermoplastic resin (A) is contained in an amount that accounts for 30 to 65 volume percent of the entire molding composition, the wax or organic compound (B) is contained in an amount that accounts for 30 to 65 volume percent of the entire molding composition, and the fatty acid compound (C) is contained in an amount that accounts for 3 to 15 volume percent of the entire molding composition, by injection molding or extrusion molding; The process involves heating the molded body to degrease it and obtaining a degreased molded body, The process of firing the degreased molded body, This is a method for manufacturing a quartz glass firing body, which includes [the specified element].

[0009] In this embodiment, it is preferable to include a step of extracting and degreasing the wax or organic compound (B) using a solvent before the degreasing step. Furthermore, it is preferable that the solvent is water, acetone, an alcohol-based solvent, or a mixture of one or more of these. It is preferable to perform the extraction and degreasing step at a temperature of 40°C to 80°C. In the extraction and degreasing step, it is preferable to remove 30% or more by volume from the organic binder. In this embodiment, it is preferable to bake the degreased molded body in a vacuum or in air at a temperature in the range of 1200°C to 1600°C.

[0010] Another aspect of the present invention is a quartz glass powder with an average particle size of 0.5 μm or less and 0.05 μm or more that can be fired, One or more thermoplastic resins (A) selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, butyl methacrylate resin, polyethylene resin, and polyvinyl butyral resin; (B) One or more waxes selected from paraffin wax or microcrystalline wax, or one or more organic compounds selected from polyethylene glycol or pluronic surfactants; and An organic binder comprising one or more fatty acid compounds (C) selected from fatty acid esters or fatty acid amides, A molding composition comprising: the thermoplastic resin (A) is contained in an amount such that the proportion thereof in the entire molding composition is 30 to 65% by volume; the wax or organic compound (B) is contained in an amount such that the proportion thereof in the entire molding composition is 30 to 65% by volume; and the fatty acid compound (C) is contained in an amount such that the proportion thereof in the entire molding composition is 3 to 15% by volume.

Advantages of the Invention

[0011] By using the production method of the present invention, in injection molding or extrusion molding with quartz glass powder, even for a molded body with a complex shape, a defatted body without defects such as swelling and cracking can be obtained, and as a result, a sound quartz glass fired body can be obtained.

Brief Description of the Drawings

[0012] [Figure 1] It is a scheme showing the manufacturing process of a quartz glass fired body. [Figure 2] It is a scheme showing another manufacturing process of a quartz glass fired body. [Figure 3] It is a figure showing the shape of the injection molded body (wall thickness 1.8 mm) manufactured in the example. [Figure 4] It is a figure showing the shape of the extrusion molded body (wall thickness 6.0 mm) manufactured in the example. [Figure 5] It is a figure schematically showing an example of an apparatus for the process of performing extraction defatting of a molded body. [Figure 6] It is a figure schematically showing an example of an apparatus for the process of performing heat defatting of a molded body. [Figure 7] It is a photograph of the quartz glass fired body manufactured in Example 2. [Figure 8] It is a photograph of the defatted molded body manufactured in Comparative Example 1.

Modes for Carrying Out the Invention

[0013] One embodiment includes a quartz glass powder with an average particle size of 0.5 μm or less and 0.05 μm or more that can be fired, One or more thermoplastic resins (A) selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, butyl methacrylate resin, polyethylene resin, and polyvinyl butyral resin; (B) One or more waxes selected from paraffin wax or microcrystalline wax, or one or more organic compounds selected from polyethylene glycol or pluronic surfactants; and An organic binder comprising one or more fatty acid compounds (C) selected from fatty acid esters or fatty acid amides, A molding composition comprising the following steps: obtaining a molded article by molding the molding composition, wherein the thermoplastic resin (A) is contained in an amount that accounts for 30 to 65 volume percent of the entire molding composition, the wax or organic compound (B) is contained in an amount that accounts for 30 to 65 volume percent of the entire molding composition, and the fatty acid compound (C) is contained in an amount that accounts for 3 to 15 volume percent of the entire molding composition, by injection molding or extrusion molding; The process involves heating the molded body to degrease it and obtaining a degreased molded body, The process of firing the degreased molded body, This is a method for manufacturing a quartz glass firing body, which includes [the specified element].

[0014] One embodiment is a manufacturing method for obtaining a quartz glass sintered body using the scheme shown in Figure 1, for example. Specifically, a mixture of quartz glass powder and an organic binder is used as a raw material (molding composition), and a molded body is obtained by molding using a molding method such as injection molding or extrusion molding using an injection molding machine or extrusion molding machine, and this molded body is degreased and sintered to obtain the target product, a quartz glass sintered body.

[0015] The molding composition comprises quartz glass powder and an organic binder. Preferably, the quartz glass powder is sinterable with an average particle size of 0.5 μm or less and 0.05 μm or more. If the average particle size of the quartz glass powder is less than 0.05 μm, the amount of organic binder required for molding increases, making the molded body prone to deformation, cracking, blistering, and other defects during heat degreasing or extraction degreasing. Furthermore, if the average particle size of the quartz glass powder is greater than 0.5 μm, even if sintering is performed under high vacuum conditions at a firing temperature of 1600°C or higher during the firing process of the degreased molded body, internal bubbles remain in the resulting quartz glass sintered body, making it difficult to obtain a dense, highly translucent quartz glass sintered body. Hereinafter, the average particle size refers to the average particle size at 50% weight cumulative, measured using a particle size distribution analyzer compliant with the laser diffraction / scattering method (Japanese Industrial Standard JIS Z 8825:2013). For example, the SALD-2000 model manufactured by Shimadzu Corporation can be used as a particle size distribution analyzer.

[0016] The organic binder mixed with the quartz glass powder consists of the following three components: one or more thermoplastic resins selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, butyl methacrylate resin, polyethylene resin, and polyvinyl butyral resin (A); one or more waxes selected from paraffin wax or microcrystalline wax, or one or more organic compounds selected from polyethylene glycol or pluronic surfactants (B); and one or more fatty acid compounds selected from fatty acid esters or fatty acid amides (C).

[0017] The molding composition preferably contains quartz glass powder and an organic binder in a volume ratio of 30:70 to 70:30. Furthermore, it is preferable that the thermoplastic resin (A) is contained in an amount that accounts for 30 to 65% of the total molding composition by volume, the wax or organic compound (B) is contained in an amount that accounts for 30 to 65% of the total molding composition by volume, and the fatty acid compound (C) is contained in an amount that accounts for 3 to 15% of the total molding composition by volume.

[0018] In the manufacturing method of the embodiment, first, the molding composition is molded by injection molding or extrusion molding. In this case, the molding temperature is preferably in the range of 120°C to 200°C. By using various molds for injection molding or extrusion molding, a molded body having the desired shape of a quartz glass firing body can be obtained. Next, the resulting molded body is heated to degrease it. Degreasing by heating is a process to remove organic binders from the molded body. Degreasing by heating is performed in air or nitrogen, by raising the temperature for 2 to 20 hours and holding the molded body at the maximum temperature for 0.5 to 2 hours, so that the maximum temperature is in the range of 500°C to 800°C. By performing degreasing by heating the molded body, a degreased molded body without defects can be obtained. Degreasing by heating the molded body can be performed using a degreasing apparatus such as the one shown in Figure 6. Next, the degreased molded body is fired. The firing of the degreased molded body is preferably carried out under a vacuum atmosphere at a temperature in the range of 1100°C to 1600°C. By firing the degreased molded body, a sound, defect-free quartz glass firing body can be obtained.

[0019] As a variation of the manufacturing method of the embodiment, a step of extracting and degreasing the organic compound (B) of the organic binder using a solvent may be included before the degreasing step. The extraction solvent used for extraction and degreasing preferably contains water or acetone, or an alcohol-based solvent such as methanol, ethanol, or isopropyl alcohol, and a mixture of water, acetone, and an alcohol-based solvent may also be used as the extraction solvent. Extraction and degreasing of the molded body can be carried out using an extraction and degreasing apparatus such as the one shown in Figure 5. Whether or not to perform extraction and degreasing should be based on the maximum wall thickness of the quartz glass fired body intended to be manufactured by the manufacturing method of the embodiment. If the maximum wall thickness of the quartz glass fired body intended to be manufactured is relatively large, the maximum wall thickness of the molded body to be manufactured first will also be relatively large. If the organic binder is to be removed from such a molded body by heat degreasing alone, cracks and blistering may occur in the degreased molded body. Therefore, when trying to obtain a quartz glass fired body with a relatively large maximum wall thickness, it is preferable to perform degreasing by combining extraction and degreasing using a solvent with heat degreasing. This makes it possible to obtain a molded and degreased body free from defects such as cracks, fractures, and blisters, and by firing this, a defect-free fired quartz glass body can be obtained.

[0020] The manufacturing method of the embodiment can, for example, obtain a quartz glass sintered body with a maximum wall thickness of less than 2 mm. When the objective is to obtain a quartz glass sintered body with a maximum wall thickness of less than 2 mm, the organic binder can be degreased by heat degreasing alone. In this case, it is preferable to use an organic binder for the molding composition that consists of the following components: one or more thermoplastic resins selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, and butyl methacrylate resin (A1); one or more organic compounds selected from one or more waxes selected from paraffin wax or microcrystalline wax with a melting point of 40°C to 90°C (B1); and one or more fatty acid compounds selected from fatty acid esters or fatty acid amides (C1). Preferably, the molding composition contains a thermoplastic resin (A1) in an amount of 15 to 50% by volume of the entire molding composition, an organic compound (B1) in an amount of 30 to 65% by volume of the entire molding composition, and a fatty acid compound (C1) in an amount of 3 to 15% by volume of the entire molding composition.

[0021] The manufacturing process for obtaining a quartz glass sintered body with a relatively small maximum wall thickness is as follows: Using a molding composition obtained by mixing the above-mentioned quartz glass powder with an organic binder containing (A1), (B1), and (C1) above, a molded body is produced by a general molding method such as injection molding or extrusion molding at a molding temperature in the range of 120°C to 200°C, for example. Subsequently, the obtained molded body is degreased by heating in air or nitrogen at a heating rate of 5 to 20°C / hr, so that the maximum temperature reaches the range of 500°C to 800°C, for a heating time of 2 to 20 hours and holding at the maximum temperature for 0.5 to 2 hours to obtain a degreased molded body. Subsequently, the degreased molded body is fired in a vacuum atmosphere at a temperature in the range of 1100°C to 1600°C, for example, to obtain a sound quartz glass sintered body free from defects such as cracks, fractures, and blistering. In this case, heating during thermal degreasing can be carried out using, for example, an electric heater, an oven, or superheated steam. When the objective is to obtain a quartz glass sintered body with a maximum wall thickness of less than 2 mm, the quartz glass sintered body can be manufactured according to the scheme shown in Figure 1.

[0022] On the other hand, by a manufacturing method according to one of the embodiments, a quartz glass sintered body with a maximum wall thickness of 2 mm or more can be obtained, for example. When the objective is to obtain a quartz glass sintered body with a maximum wall thickness of 2 mm or more, it is desirable to complete the degreasing of the organic binder by performing extraction degreasing and heat degreasing. In this case, it is preferable to use an organic binder for the molding composition that consists of the following components: one or more thermoplastic resins selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polyethylene resin, and polyvinyl butyral resin (A2); one or more organic compounds selected from paraffin wax, polyethylene glycol, or pluronic surfactants with a melting point of 40°C to 70°C (B2); and one or more fatty acid compounds selected from fatty acid esters or fatty acid amides (C2). Preferably, the molding composition contains a thermoplastic resin (A2) in an amount of 30 to 65% by volume of the entire molding composition, an organic compound (B2) in an amount of 30 to 65% by volume of the entire molding composition, and a fatty acid compound (C2) in an amount of 3 to 15% by volume of the entire molding composition.

[0023] The manufacturing process for obtaining a quartz glass fired body with a relatively large maximum wall thickness is as follows: Using a molding composition obtained by mixing the above-mentioned quartz glass powder with an organic binder containing (A2), (B2), and (C2), a molded body is produced by a general molding method such as injection molding or extrusion molding at a molding temperature in the range of 120°C to 200°C, for example. Subsequently, extraction degreasing is performed using an extraction solvent consisting of at least one of the following: water, acetone, alcohols, etc., to obtain an extracted and degreased molded body. The obtained extracted and degreased molded body is then heated and degreased in air or nitrogen, with a heating time of 2 to 20 hours and holding at the maximum temperature for 0.5 to 2 hours, so that the maximum temperature is in the range of 500°C to 800°C, to obtain a degreased molded body. Subsequently, the degreased molded body is fired in a vacuum atmosphere at a temperature in the range of 1100°C to 1600°C, for example, to obtain a sound quartz glass fired body without defects such as cracks, fractures, or blistering. In this case, if the heating time during heat degreasing is less than 2 hours, cracks and blistering are likely to occur in the degreased molded product. Furthermore, heating during heat degreasing can be carried out using, for example, an electric heater, an oven, or superheated steam. When the objective is to obtain a quartz glass sintered body with a maximum wall thickness of 2 mm or more, the quartz glass sintered body can be manufactured according to the scheme shown in Figure 2.

[0024] A second embodiment of the present invention is a molding composition. The molding composition of the second embodiment is suitably used in the manufacturing method of the first embodiment. The molding composition of the second embodiment comprises a quartz glass powder with a calcinable average particle size of 0.5 μm or less and 0.05 μm or more, One or more thermoplastic resins (A) selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, butyl methacrylate resin, polyethylene resin, and polyvinyl butyral resin; (B) One or more waxes selected from paraffin wax or microcrystalline wax, or one or more organic compounds selected from polyethylene glycol or pluronic surfactants; and An organic binder comprising one or more fatty acid compounds (C) selected from fatty acid esters or fatty acid amides, A molding composition comprising the thermoplastic resin (A) in an amount that accounts for 30 to 65% by volume of the entire molding composition, the wax or organic compound (B) in an amount that accounts for 30 to 65% by volume of the entire molding composition, and the fatty acid compound (C) in an amount that accounts for 3 to 15% by volume of the entire molding composition.

[0025] The quartz glass powder used in the molding composition preferably has an average particle size of 0.05 μm or more and 0.5 μm or less. If the average particle size of the quartz glass powder is less than 0.05 μm, the amount of organic binder required for molding increases, making the molded body prone to deformation, cracking, blistering, and other defects during extraction degreasing or heat degreasing. Furthermore, if the average particle size of the quartz glass powder is greater than 0.5 μm, even if sintering is performed in a high vacuum state at a firing temperature of 1600°C or higher during the firing process of the degreased molded body, air bubbles remain inside the degreased molded body, making it difficult to obtain a dense, highly translucent quartz glass fired body. In this specification, the average particle size refers to the particle size at 50% cumulative weight, measured using a particle size distribution analyzer that employs the laser diffraction / scattering method. A Shimadzu SALD-2000 model can be used as the particle size distribution analyzer.

[0026] The molding composition of the second embodiment is used to produce molded articles by general molding methods such as injection molding or extrusion molding. The obtained molded articles are then subjected to heat degreasing to remove the organic binder from the molded articles to obtain degreased molded articles, and subsequently the degreased molded articles are fired to obtain quartz glass fired articles.

[0027] The molding composition of the second embodiment may be used to produce a molded body by a general molding method such as injection molding or extrusion molding, then to perform extraction and degreasing using a suitable extraction solvent to obtain an extracted and degreasing molded body, then to perform heat degreasing on the extracted and degreasing molded body to obtain a degreased molded body, and subsequently to calcine the degreased molded body to obtain a calcined quartz glass body.

[0028] Whether to degrease the molded body by heat degreasing alone or by a combination of heat degreasing and extraction degreasing can be determined by the maximum wall thickness of the quartz glass firing body to be manufactured. If the maximum wall thickness of the quartz glass firing body is less than 2 mm, the organic binder contained in the molding composition preferably contains the following components: one or more thermoplastic resins selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, and butyl methacrylate resin (A1); one or more organic compounds selected from one or more waxes selected from paraffin wax or microcrystalline wax with a melting point of 40°C to 90°C (B1); and one or more fatty acid compounds selected from fatty acid esters or fatty acid amides (C1). Preferably, the molding composition contains thermoplastic resin (A1) in an amount of 15 to 50 volume percent of the total molding composition, organic compound (B1) in an amount of 30 to 65 volume percent of the total molding composition, and fatty acid compound (C1) in an amount of 3 to 15 volume percent of the total molding composition. If the content of thermoplastic resin (A1) in the molding composition is less than 30 volume percent, the molded article formed from the molding composition may become brittle. Also, swelling and cracking may occur in the degreased molded article obtained by degreasing the molded article. Furthermore, if the content of thermoplastic resin (A1) in the molding composition is more than 65 volume percent, the viscosity during molding will increase, making it difficult to mold molded articles with complex shapes. If the melting point of organic compound (B1) is lower than 40°C, the organic compound (B1) is more likely to separate from the molded article, and the moldability will deteriorate. Furthermore, in order to improve fluidity during molding, the fatty acid ester added to the fatty acid compound (C1) is used in an amount of 3 to 15% by volume. However, if the amount added is less than 3%, the fluidity will be poor, and bubbles and weld cracks will often occur in the molded product. Also, if the amount added exceeds 15%, the molded product tends to become brittle. In the method for manufacturing the molded product, phthalic acid esters, polyethylene wax, polypropylene wax, and ester waxes such as carnauba wax and montan wax may be added to the molding composition as additives for the purpose of improving the moldability of the molding composition. From molded articles produced from such molding compositions, the organic binder can be removed by heat degreasing alone.

[0029] On the other hand, when the maximum wall thickness of the quartz glass fired body is 2 mm or more, the organic binder contained in the molding composition preferably contains the following components: one or more thermoplastic resins (A2) selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polyethylene resin, and polyvinyl butyral resin; one or more organic compounds (B2) selected from paraffin wax, polyethylene glycol, or pluronic surfactants having a melting point of 40°C to 70°C; and one or more fatty acid compounds (C2) selected from fatty acid esters or fatty acid amides. Preferably, the thermoplastic resin (A2) is contained in an amount that accounts for 30 to 65 volume% of the entire molding composition, the organic compound (B2) is contained in an amount that accounts for 30 to 65 volume% of the entire molding composition, and the fatty acid compound (C2) is contained in an amount that accounts for 3 to 15 volume% of the entire molding composition. If the content of thermoplastic resin (A2) in the molding composition is less than 30 volume%, the molded body formed from the molding composition may become brittle. Furthermore, blistering and cracking may occur in the degreased molded article obtained by degreasing the molded article. Also, if the content of thermoplastic resin (A2) in the molding composition is greater than 65% by volume, the viscosity during molding will increase, making it difficult to mold molded articles with complex shapes. If the melting point of organic compound (B2) is lower than 40°C, the organic compound (B2) will easily separate from the molded article, resulting in poor moldability. Also, if the melting point of organic compound (B2) is higher than 59°C, the extraction rate of organic compound (B2) in the extraction degreasing process will decrease significantly, and blistering and cracking may occur in the molded article during the subsequent heat degreasing process. In the method for manufacturing molded articles, fatty acid esters, polyethylene wax, polypropylene wax, and ester waxes such as carnauba wax and montane wax may be added to the molding composition as additives for the purpose of improving the moldability of the molding composition. From molded articles produced from such molding compositions, organic binders can be removed by a combination of extraction degreasing and heat degreasing.

[0030] The invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereto. [Examples]

[0031] [Example 1] Polystyrene (PS, Dick Styrene: CR3500) was used as the thermoplastic resin (A), along with ethylene vinyl acetate copolymer (EVA633: Tosoh EVA633), butyl methacrylate (PBMA, Sanyo Chemical: CB-1), paraffin wax (melting point 46°C) as the organic compound (B), and stearic acid as the fatty acid compound (C). These were put into a batch mixer and melted uniformly. Next, quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) was added and the mixture was kneaded at 180°C for 60 minutes. The kneaded mixture was removed from the batch mixer and pulverized to obtain a molding composition.

[0032] Molding composition Quartz glass powder: 47% by volume Organic binder: 53% by volume (Organic binder) Polystyrene (thermoplastic resin (A)): 15% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 15% by volume Polybutyl methacrylate (thermoplastic resin (A)): 15% by volume Paraffin wax (organic compound (B)): 40% by volume Stearic acid (fatty acid compound (C)): 5% by volume Furthermore, to improve moldability, 10% by volume of carnauba wax was added to the organic binder.

[0033] Using the obtained molding composition, injection molding was performed at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 3 (thickness 1.5 mm, width 6 mm, length 20 mm). The obtained molded body was heated in the degreasing furnace shown in Figure 6 from room temperature to 500°C over 28 hours, and then the furnace was cooled to obtain a degreased molded body. The obtained degreased molded body was held in a firing furnace in a vacuum at 1550°C for 2 hours, and then the furnace was cooled to obtain a fired quartz glass body. The obtained fired quartz glass body was sound, free from defects such as cracks and blistering, and had a firing density of 2.2 g / cm³. 3 (The relative density was 100%).

[0034] [Example 2] High-density polyethylene (HDPE, Asahi Kasei Suntech J300) was used as the thermoplastic resin (A), ethylene vinyl acetate copolymer (EVA633, Tosoh EVA633), paraffin wax (melting point 46°C) as the organic compound (B), and stearic acid as the fatty acid compound (C). These were put into a batch kneader and melted uniformly. Then, quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) was added and kneaded at 180°C for 60 minutes. The kneaded material was removed from the batch kneader and pulverized to obtain a molding composition.

[0035] Molding composition Quartz glass powder: 47% by volume Organic binder: 53% by volume (Organic binder) High-density polyethylene (thermoplastic resin (A)): 22% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 23% by volume Paraffin wax (organic compound (B)): 45% by volume Stearic acid (fatty acid compound (C): 5% by volume) Furthermore, to improve moldability, 5% by volume of carnauba wax was added to the organic binder.

[0036] Using the obtained molding composition, injection molding was performed at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 4 (thickness 6 mm, width 6 mm, length 20 mm). The obtained molded body was immersed in acetone at a temperature of 52°C in the extraction degreasing furnace shown in Figure 5 and extracted and degreased for 8 hours to obtain a degreased molded body. Next, in the heating degreasing furnace shown in Figure 6, the temperature was raised from room temperature to 500°C over 12 hours, and then the furnace was cooled to perform degreasing and obtain a degreased molded body. The obtained degreased molded body was held in a firing furnace in air at 1550°C for 2 hours, and then the furnace was cooled to obtain a quartz glass firing body. The obtained quartz glass firing body was sound, free from defects such as cracks and blistering, and the firing density was 2.2 g / cm³. 3 (The relative density was 100%) (Figure 7).

[0037] [Example 3] Polystyrene (PS, Dick Styrene: CR3500) was used as the thermoplastic resin (A), along with ethylene vinyl acetate copolymer (EVA633: Tosoh EVA633), butyl methacrylate (PBMA, Sanyo Chemical: CB-1), paraffin wax (melting point 46°C) as the organic compound (B), and stearic acid as the fatty acid compound (C). These were put into a batch mixer and melted uniformly. Next, quartz glass powder (Admatex, Admanano: YC100C, average particle size 0.01 μm) and quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) were added and the mixture was kneaded at 180°C for 60 minutes. The kneaded mixture was removed from the batch mixer and pulverized to obtain a molding composition.

[0038] Molding composition Quartz glass powder: 45% by volume Organic binder: 55% by volume (Quartz glass powder) Quartz glass powder YC100C: 10 volumes Quartz glass powder SO-E1: 90% by volume (Organic binder) Polystyrene (thermoplastic resin (A)): 15% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 15% by volume Polybutyl methacrylate (thermoplastic resin (A)): 15% by volume Paraffin wax (organic compound (B)): 40% by volume Stearic acid (fatty acid compound (C)): 5% by volume Furthermore, to improve moldability, 10% by volume of carnauba wax was added to the organic binder.

[0039] The obtained molding composition was extruded at a molding temperature of 180°C to obtain a molded body with a thickness of 1 mm, a width of 6 mm, and a length of 20 mm. The obtained molded body was heated in a degreasing furnace from room temperature to 500°C over 24 hours, and then the furnace was cooled to obtain a degreased molded body. The obtained degreased molded body was held in a firing furnace under vacuum at 1600°C for 2 hours, and then the furnace was cooled to obtain a fired quartz glass body. The obtained fired quartz glass body was sound, free from defects such as cracks and blistering, and was transparent. The firing density was 2.2 g / cm³. 3 (The relative density was 100%).

[0040] [Example 4] Polystyrene (PS, Dick Styrene: CR3500) was used as the thermoplastic resin (A), along with ethylene vinyl acetate copolymer (EVA633: Tosoh EVA633), butyl methacrylate (PBMA, Sanyo Chemical: CB-1), paraffin wax (melting point 46°C) and microcrystalline wax (melting point 64°C) as organic compounds (B), and stearic acid as a fatty acid compound (C). These were put into a batch mixer and uniformly melted. Next, quartz glass powder (Admatex, Admanano: YC100, average particle size 0.01 μm) and quartz glass powder (Admatex, Admafine: SO-E11, average particle size 0.3 μm) were added and kneaded at 180°C for 60 minutes. The kneaded mixture was removed from the batch mixer and pulverized to obtain a molding composition.

[0041] Molding composition Quartz glass powder: 45% by volume Organic binder: 55% by volume (Quartz glass powder) Quartz glass powder YC100C: 10 volumes Quartz glass powder SO-E1: 90% by volume (Organic binder) Polystyrene (thermoplastic resin (A)): 15% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 15% by volume Polybutyl methacrylate (thermoplastic resin (A)): 15% by volume Paraffin wax (organic compound (B)): 30% by volume Microcrystalline wax (organic compound (B)): 10% by volume Stearic acid (fatty acid compound (C)): 5% by volume Furthermore, to improve moldability, 10% by volume of carnauba wax was added to the organic binder.

[0042] The obtained molding composition was extruded at a molding temperature of 180°C to obtain a molded body with a thickness of 1 mm, a width of 6 mm, and a length of 20 mm. The obtained molded body was heated in a degreasing furnace from room temperature to 500°C over 24 hours, and then the furnace was cooled to obtain a degreased molded body. The obtained degreased molded body was held in a firing furnace in a vacuum at 1600°C for 2 hours, and then the furnace was cooled to obtain a fired quartz glass body. The obtained fired quartz glass body was sound, free from defects such as cracks and blistering, and was transparent. The firing density was 2.2 g / cm³. 3 (The relative density was 100%).

[0043] [Example 5] High-density polyethylene (HDPE, Asahi Kasei Suntech J300) was used as the thermoplastic resin (A), ethylene vinyl acetate copolymer (EVA633, Tosoh EVA633), paraffin wax (melting point 46°C) as the organic compound (B), and stearic acid as the fatty acid compound (C). These were put into a batch mixer and melted uniformly. Then, quartz glass powder (Admatex, Admanano: YC100C, average particle size 0.01 μm) and quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) were added and the mixture was kneaded at 180°C for 60 minutes. The kneaded mixture was removed from the batch mixer and pulverized to obtain a molding composition.

[0044] Molding composition Quartz glass powder: 45% by volume Organic binder: 55% by volume (Quartz glass powder) Quartz glass powder YC100: 10% by volume Quartz glass powder SO-E1: 90% by volume (Organic binder) High-density polyethylene (thermoplastic resin (A)): 20% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 20% by volume Paraffin wax (organic compound (B)): 45% by volume Stearic acid (fatty acid compound (C)): 10% by volume Furthermore, to improve moldability, 5% by volume of carnauba wax was added to the organic binder.

[0045] Using the obtained molding composition, injection molding was performed at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 3 (thickness 6 mm, width 6 mm, length 20 mm). The obtained molded body was immersed in isopropyl alcohol at a temperature of 70°C in the extraction degreasing furnace shown in Figure 5 and extracted and degreased for 8 hours to obtain a degreased molded body. Next, the degreased molded body was heated in a heating degreasing furnace from 200°C to 500°C over 5 hours, and then the furnace was cooled to obtain a degreased molded body. The obtained degreased molded body was held in a firing furnace under vacuum at 1500°C for 2 hours, and then the furnace was cooled to obtain a fired quartz glass body. The obtained fired quartz glass body had high transparency, was sound and free from defects such as cracks and blistering, and had a firing density of 2.2 g / cm³. 3 (The relative density was 100%).

[0046] [Example 6] Polypropylene (PP, Asahi Kasei, Sun Allomer PMB60A) and high-density polyethylene (HDPE, Asahi Kasei Suntech J300) were used as thermoplastic resins (A), ethylene vinyl acetate copolymer (EVA633, Tosoh EVA633), paraffin wax (melting point 46°C) and pluronic surfactant (Sanyo Chemical, Newpol PE68) as organic compounds (B), and stearic acid amide as a fatty acid compound (C) were used. These were put into a batch mixer and melted uniformly. Next, quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) was added and kneaded at 180°C for 60 minutes. The kneaded material was removed from the batch mixer and pulverized to obtain a molding composition.

[0047] Molding composition Quartz glass powder: 45% by volume Organic binder: 55% by volume (Quartz glass powder) Quartz glass powder YC100C: 10% by volume Quartz glass powder SO-E1: 90% by volume (Organic binder) High-density polyethylene (thermoplastic resin (A)): 20% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 20% by volume Paraffin wax (organic compound (B)): 25% by volume Pluronic surfactant (organic compound (B)): 20% by volume Stearic acid amide (fatty acid compound (C)): 10% by volume Furthermore, to improve moldability, 5% by volume of carnauba wax was added to the organic binder.

[0048] Using the obtained molding composition, injection molding was performed at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 3 (thickness 6 mm, width 6 mm, length 20 mm). The obtained molded body was immersed in isopropyl alcohol at a temperature of 70°C in the extraction degreasing furnace shown in Figure 5 and extracted and degreased for 8 hours to obtain a degreased molded body. Next, the degreased molded body was heated in a heating degreasing furnace from 200°C to 500°C over 5 hours, and then the furnace was cooled to obtain a degreased molded body. The obtained degreased molded body was held in a firing furnace under vacuum at 1500°C for 2 hours, and then the furnace was cooled to obtain a fired quartz glass body. The obtained fired quartz glass body had high transparency, was sound and free from defects such as cracks and blistering, and had a firing density of 2.2 g / cm³. 3 (The relative density was 100%).

[0049] [Example 7] Low-density polyethylene (LDPE, Asahi Kasei Suntech M6555), ethylene vinyl acetate copolymer (EVA, Tosoh EVA722), and polyvinyl butyral (PVB, Sekisui Chemical, BL-10) were used as thermoplastic resins (A), polyethylene glycol (PEG2000) and a pluronic surfactant (Sanyo Chemical, Newpol PE68) were used as organic compounds (B), and stearic acid amide was used as a fatty acid compound (C). These were put into a batch mixer and uniformly melted. Next, quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) was added and kneaded at 180°C for 60 minutes. The kneaded material was removed from the batch mixer and pulverized to obtain a molding composition.

[0050] Molding composition Quartz glass powder: 45% by volume Organic binder: 55% by volume (Quartz glass powder) Quartz glass powder YC100C: 10% by volume Quartz glass powder SO-E1: 90% by volume (Organic binder) Low-density polyethylene (thermoplastic resin (A)): 10% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 30% by volume Polyvinyl butyral (thermoplastic resin (A)): 5% by volume Polyethylene glycol (organic compound (B)): 25% by volume Pluronic surfactant (organic compound (B)): 20% by volume Stearic acid amide (fatty acid compound (C)): 10% by volume

[0051] Using the obtained molding composition, injection molding was performed at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 3 (thickness 6 mm, width 6 mm, length 20 mm). The obtained molded body was immersed in water at 70°C in the extraction degreasing furnace shown in Figure 5 for 8 hours to extract and degrease it, obtaining a degreased molded body. Next, the degreased molded body was heated in a heating degreasing furnace from 200°C to 500°C over 5 hours, and then the furnace was cooled to obtain a degreased molded body. The obtained degreased molded body was held in a firing furnace under vacuum at 1500°C for 2 hours, and then the furnace was cooled to obtain a fired quartz glass body. The obtained fired quartz glass body had high transparency, was sound and free from defects such as cracks and blisters, and had a firing density of 2.2 g / cm³. 3 (The relative density was 100%).

[0052] [Comparative Example 1] Polystyrene (PS, Dick Styrene: CR3500) was used as the thermoplastic resin (A), along with ethylene vinyl acetate copolymer (EVA633: Tosoh EVA633), butyl methacrylate (PBMA, Sanyo Chemical: CB-1), paraffin wax (melting point 46°C) as the organic compound (B), and stearic acid as the fatty acid compound (C). These were put into a batch mixer and melted uniformly. Next, quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) was added and the mixture was kneaded at 180°C for 60 minutes. The kneaded mixture was removed from the batch mixer and pulverized to obtain a molding composition.

[0053] Molding composition Quartz glass powder: 47% by volume Organic binder: 53% by volume (Organic binder) Polystyrene (thermoplastic resin (A)): 25% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 25% by volume Polybutyl methacrylate (thermoplastic resin (A)): 25% by volume Paraffin wax (organic compound (B)): 10% by volume Stearic acid (fatty acid compound (C)): 5% by volume Furthermore, to improve moldability, 10% by volume of carnauba wax was added to the organic binder.

[0054] Using the obtained molding composition, injection molding was performed at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 4 (thickness 6 mm, width 6 mm, length 20 mm). The obtained molded body was degreased by heating in a degreasing furnace from room temperature to 500°C for 28 hours. The degreased molded body developed cracks and blistering, making further firing impossible.

[0055] [Comparative Example 2] High-density polyethylene (HDPE, Asahi Kasei Suntech J300) was used as the thermoplastic resin (A), ethylene vinyl acetate copolymer (EVA633, Tosoh EVA633), paraffin wax (melting point 46°C) as the organic compound (B), and stearic acid as the fatty acid compound (C). These were put into a batch kneader and melted uniformly. Then, quartz glass powder (Admatex, Admafine: SO-E1, average particle size 0.3 μm) was added and kneaded at 180°C for 60 minutes. The kneaded material was removed from the batch kneader and pulverized to obtain a molding composition.

[0056] Molding composition Quartz glass: 47% by volume Organic binder: 53% by volume (Organic binder) High-density polyethylene (thermoplastic resin (A)): 35% by volume Ethylene vinyl acetate (thermoplastic resin (A)): 35% by volume Paraffin wax (organic compound (B)): 15% by volume Stearic acid (fatty acid compound (C): 10% by volume) Furthermore, to improve moldability, 5% by volume of carnauba wax was added to the organic binder.

[0057] Using the obtained molding composition, injection molding was performed at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 4 (thickness 6 mm, width 6 mm, length 20 mm). The obtained molded body was immersed in acetone at a temperature of 52°C in the extraction degreasing furnace shown in Figure 5 and extracted and degreased for 8 hours to obtain a degreased molded body. Next, the degreased molded body was heated in the heating degreasing furnace shown in Figure 6 from room temperature to 500°C over 12 hours, and then the furnace was cooled to perform heat degreasing. However, blister cracks occurred in the quartz glass fired body, so the firing process could not be completed.

[0058] [Examples 5-12, Comparative Examples 4-7] Furthermore, experiments were conducted by varying the organic binder components to obtain quartz glass fired bodies with a wall thickness of 2 mm or more. The compositions of the organic binders used are shown in Table 1, and the compositions and results for injection molding are shown in Table 2. The mixing, degreasing, and firing conditions were carried out in accordance with Example 1. The molded bodies shown in Figure 4 were used for the wall thickness of the molded bodies.

[0059] The notation in Table 1 is as follows: (Quartz glass powder) Admatex, AdmaFine: SO-E1 (Organic binder) (Thermoplastic resin (A)) Polystyrene (PS, Dick Styrene CR3500) Polypropylene (PP, Nippon Polypropylene BC06C) Ethylene vinyl acetate copolymer (EVA, Tosoh EVA722) Polyvinyl butyral (PBMA, Sanyo Chemical CB-1) (Organic compound (B)) Paraffin wax (melting point 46℃): F-115 Paraffin wax (melting point 53℃): F-125 (Fatty acid compounds (C)) Stearic acid (Other additives) Carnauba wax CWAX

[0060] [Table 1] Table 1: Organic binder formulation

[0061] [Table 2] Table 2: Molding, degreasing, and firing results

[0062] In Table 2, for Examples 5 to 12, an organic binder was incorporated within the scope of the present invention (A to H in Table 1). The organic binder was mixed at a ratio of 45 volume% to 55 volume% of quartz glass powder (primary particle size 0.2 μm), and the mixture was heated and kneaded at 180°C. The resulting molding composition was injection molded at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 3 (thickness 1.8 mm, width 6 mm, length 20 mm). The obtained molded body was heated in the degreasing furnace shown in Figure 5 from 50°C to 500°C over 24 hours, and then the furnace was cooled to obtain a degreased molded body. At this point, a sound degreased molded body was obtained, so the obtained degreased molded body was fired in a firing furnace under a vacuum atmosphere at 1500°C. The resulting quartz glass fired bodies were free from cracks and blistering, and all were sound transparent quartz glass fired bodies with a firing density of 99.9% or higher. The test results are shown in Table 2.

[0063] On the other hand, for Comparative Examples 4 to 7, organic binders were formulated with components outside the scope of the present invention (Table 1, a to e), and molding compositions were obtained under the same conditions as Examples 5 to 12, and molded articles were obtained under the same conditions as Examples 5 to 12. In the case of Comparative Example 7, the obtained molded article was very brittle, and a sound molded article could not be obtained. In the case of Comparative Examples 4 to 6, heat degreasing was performed under the same conditions as Examples 5 to 12, but the obtained degreased molded articles showed blistering and cracking as shown in Table 2, and were not sound degreased molded articles.

[0064] The notation in Table 3 is as follows: (Quartz glass powder) Admatex, AdmaFine: SO-E1: 15% by volume Admatex, Admanano: YC100C: 85% by volume (Organic binder) (Thermoplastic resin (A)) High-density polyethylene (HDPE, Japan Polyethylene HJ560) Polypropylene (PP, Nippon Polypropylene BC06C) Ethylene vinyl acetate copolymer (EVA, Tosoh EVA633) (Organic compound (B)) Paraffin wax (melting point 46℃): F-115, Pluronic surfactant (PE68) Pluronic surfactant (Sanyo Chemical, Newpol PE68) (Fatty acid compounds (C)) Stearic acid (Other additives) Carnauba wax CWAX

[0065] [Table 3]

[0066] [Table 4]

[0067] In Table 4, for Examples 13 to 20, an organic binder was incorporated within the scope of the present invention (see Table 3, Parts 1-2), with the organic binder being blended at a ratio of 55% by volume to 52% by volume of quartz glass powder. The mixture was heated and kneaded at 180°C, and the resulting molding composition was injection molded at a molding temperature of 180°C to obtain a molded body having the shape shown in Figure 3 (thickness 6 mm, width 6 mm, length 20 mm). The obtained molded body was degreased by extraction by immersion in acetone or isopropyl alcohol in a container heated to 50°C for 8 hours using the solvent degreasing furnace shown in Figure 5. Then, the temperature was raised from 50°C to 500°C over 18 hours in a heating degreasing furnace, and the furnace was then cooled to obtain a degreased molded body. At this point, a sound degreased molded body was obtained, so the obtained degreased molded body was fired in a firing furnace under a vacuum atmosphere at 1500°C. The resulting quartz glass firing bodies were free from cracks and blistering, and all were sound firing bodies with a firing density of 99.9% or higher.

[0068] On the other hand, for Comparative Examples 8 to 11, organic binders were formulated with components outside the scope of the present invention (Table 1, s to su), and molding compositions were obtained under the same conditions as Examples 13 to 20, and molded articles were obtained under the same conditions as Examples 13 to 20. For Comparative Examples 10 and 11, the obtained molded articles were very brittle, and sound molded articles could not be obtained. For Comparative Examples 8 and 9, extraction and degreasing were performed under the same conditions as Examples 13 to 20, but the obtained molded articles after extraction and degreasing showed blistering and cracking, and sound molded articles after extraction and degreasing could not be obtained.

[0069] Furthermore, when extraction degreasing was performed using the molded articles of Examples 13 to 15 such that the extraction rate of the total organic binder was less than 30% by volume, and the subsequent heat degreasing conditions were a heating rate of 200°C / hr, cracks and blistering occurred in the resulting degreased molded articles. From this, it was confirmed that it is preferable to perform extraction degreasing such that the extraction rate of the total organic binder is 30% by volume or more. [Industrial applicability]

[0070] Using the molding composition of the present invention, it was possible to obtain a defect-free, sound, complexly shaped quartz glass firing body in a short time. This invention can facilitate the use of complex-shaped parts in medical-related components, automotive parts, and communication equipment components.

Claims

1. Quartz glass powder with an average particle size of 0.5 μm or less and 0.05 μm or more that can be fired, One or more thermoplastic resins (A) selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, butyl methacrylate resin, polyethylene resin, and polyvinyl butyral resin; One or more waxes selected from paraffin wax or microcrystalline wax, or one or more organic compounds selected from polyethylene glycol or pluronic surfactants (B); and An organic binder comprising one or more fatty acid compounds (C) selected from fatty acid esters or fatty acid amides, A molding composition comprising the following steps: obtaining a molded article by molding the molding composition, wherein the thermoplastic resin (A) is contained in an amount that accounts for 30 to 65 volume percent of the entire molding composition, the wax or organic compound (B) is contained in an amount that accounts for 30 to 65 volume percent of the entire molding composition, and the fatty acid compound (C) is contained in an amount that accounts for 3 to 15 volume percent of the entire molding composition, by injection molding or extrusion molding; The process involves heating the molded body to degrease it and obtaining a degreased molded body, The process of firing the degreased molded body, A method for manufacturing a quartz glass firing body, including the method described above.

2. The manufacturing method according to claim 1, further comprising the step of extracting and degreasing the wax or organic compound (B) using a solvent before the degreasing step.

3. The manufacturing method according to claim 2, wherein the solvent is water, acetone, an alcohol-based solvent, or a mixture of one or more of these.

4. The manufacturing method according to claim 2, wherein the extraction and degreasing step is performed at a temperature of 40°C to 80°C.

5. The manufacturing method according to claim 3, wherein the extraction and degreasing step is performed at a temperature of 40°C to 80°C.

6. The manufacturing method according to claim 2, wherein 30% by volume or more of the organic binder is removed in the extraction and degreasing step.

7. The manufacturing method according to claim 3, wherein 30% by volume or more of the organic binder is removed in the extraction and degreasing step.

8. The manufacturing method according to claim 4, wherein 30% by volume or more of the organic binder is removed in the extraction and degreasing step.

9. The manufacturing method according to claim 5, wherein 30% by volume or more of the organic binder is removed in the extraction and degreasing step.

10. The manufacturing method according to any one of claims 1 to 9, wherein the degreased molded body is fired in a vacuum or in air at a temperature in the range of 1200°C to 1600°C.

11. Quartz glass powder with an average particle size of 0.5 μm or less and 0.05 μm or more that can be fired, One or more thermoplastic resins (A) selected from the group consisting of polypropylene resin, ethylene-vinyl acetate copolymer resin, polystyrene resin, butyl methacrylate resin, polyethylene resin, and polyvinyl butyral resin; One or more waxes selected from paraffin wax or microcrystalline wax, or one or more organic compounds selected from polyethylene glycol or pluronic surfactants (B); and An organic binder comprising one or more fatty acid compounds (C) selected from fatty acid esters or fatty acid amides, A molding composition comprising the following: the thermoplastic resin (A) is contained in an amount that accounts for 30 to 65% by volume of the entire molding composition; the wax or organic compound (B) is contained in an amount that accounts for 30 to 65% by volume of the entire molding composition; and the fatty acid compound (C) is contained in an amount that accounts for 3 to 15% by volume of the entire molding composition.

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