JP-7855502-B2 - Porous glass substrate manufacturing system and glass substrate manufacturing method

JP7855502B2JP 7855502 B2JP7855502 B2JP 7855502B2JP-7855502-B2

Inventors

野田直人
飯沼均

Assignees

信越化学工業株式会社

Dates

Publication Date: 20260508
Application Date: 20221215

Claims (5)

A raw material tank in which liquid organic siloxane raw materials are stored, with the remaining space filled with inert gas, A liquid transfer pump for transferring the organic siloxane raw material from the raw material tank, A circulation pipe and branch pipe through which the organic siloxane raw material, which is supplied by the aforementioned liquid transfer pump, A liquid mass flow controller that controls the flow rate of the organic siloxane raw material through the branched piping to a predetermined flow rate, A vaporizer is provided downstream of the liquid mass flow controller to vaporize the organic siloxane raw material, A raw material supply device equipped with, A porous glass base material manufacturing apparatus is installed inside a building and includes a burner that burns the organic siloxane raw material vaporized by the vaporizer to produce silica fine particles, Equipped with, The porous glass base material manufacturing system is characterized in that the raw material supply device is installed inside a separate building from the building, which is not affected by the temperature changes of the porous glass base material manufacturing apparatus, and the room temperature inside the building not affected by the temperature changes of the porous glass base material manufacturing apparatus is maintained at 30°C .
A porous glass base material manufacturing system according to claim 1, wherein a raw material liquid supply unit comprising the raw material tank and the liquid transfer pump, and a raw material vaporization unit comprising the liquid mass flow controller and the vaporizer are provided in separate buildings, and the indoor temperature of both the building of the raw material liquid supply unit and the building of the raw material vaporization unit is maintained at 30°C .
The porous glass base material manufacturing system according to claim 2, wherein one or more sets of raw material vaporization units are installed in one porous glass base material manufacturing apparatus, each set is installed in a separate building, and the indoor temperature of each set's building is maintained at 30°C .
The porous glass matrix manufacturing system according to any one of claims 1 to 3, wherein the organic siloxane raw material is octamethylcyclotetrasiloxane (OMCTS).
A step of manufacturing a porous glass base material using the porous glass base material manufacturing system described in claim 1, The steps include: manufacturing a glass base material by converting the porous glass base material into transparent glass; A method for manufacturing a glass base material.

Description

This invention relates to a porous glass base material manufacturing system and a method for manufacturing a glass base material, comprising a raw material supply device and a porous glass base material manufacturing device. Conventionally, a method for manufacturing porous glass substrates is known, in which silica nanoparticles ( SiO₂ nanoparticles) are deposited on a starting material such as a glass rod to form a soot. By dehydrating and sintering this type of porous glass substrate, a glass substrate for manufacturing optical fibers and the like can be obtained. Porous glass matrix materials are manufactured, for example, by externally depositing SiO₂ nanoparticles onto a core matrix material produced by the VAD method, using the OVD method. Silicon tetrachloride ( SiCl₄ ) is widely used as a silicon compound raw material for generating SiO₂ nanoparticles. By supplying SiCl₄ to a burner and performing flame hydrolysis, SiO₂ fine particles are generated according to the following formula. SiCl 4 +2H 2 O→SiO 2 +4HCl This flame hydrolysis process produces hydrochloric acid as a byproduct. Therefore, if moisture is present, it becomes corrosive to metals, requiring careful attention to the materials used in the manufacturing equipment and exhaust temperature control. While it is possible to install equipment to recover and treat the hydrochloric acid from the exhaust, this would increase costs. For producing SiO₂ nanoparticles, halogen-free organosilicon compounds that do not contain Cl (chlorine) within their molecules are sometimes used as silicon compound raw materials. One example is octamethylcyclotetrasiloxane (OMCTS), a high-purity organosilicon available on an industrial scale. When OMCTS is used, SiO2 nanoparticles are generated based on the following formula. [SiO(CH 3 ) 2 ] 4 +16O 2 →4SiO 2 +8CO 2 +12H 2 O Using halogen-free organic siloxanes, such as OMCTS, as silicon compound raw materials eliminates the emission of hydrochloric acid, thus increasing flexibility in handling manufacturing equipment materials and exhaust gases. Furthermore, the elimination of the need for hydrochloric acid recovery treatment facilities can lead to cost reductions. In addition, OMCTS has a very high heat of combustion, and it is expected that the amount of combustible gases such as hydrogen required for combustion will be reduced compared to when SiCl4 is used. Patent No. 6793676 This figure shows an example configuration of the porous glass substrate manufacturing system of the present invention.This figure shows another example configuration of the porous glass substrate manufacturing system of the present invention.This figure shows yet another example configuration of the porous glass substrate manufacturing system of the present invention. The embodiments of the present invention will be described below with reference to the drawings. In the following description and drawings, the same parts will be denoted by the same reference numerals, and parts that have already been described will be omitted or described only as necessary. Figure 1 shows an example configuration of the porous glass base material manufacturing system of the present invention. The porous glass base material manufacturing system of the present invention comprises a raw material supply device and a porous glass base material manufacturing device 200. Figure 1 shows an example with three porous glass base material manufacturing devices 200 installed, but the number of installed devices is arbitrary and can be one or multiple units. The raw material supply system comprises a raw material tank 112, circulation piping 113, liquid transfer pump 114, pressure loss unit 115, pressure reducing valve 131, liquid mass flow controller 132, and vaporizer 133. Of these, the raw material tank 112, circulation piping 113, liquid transfer pump 114, and pressure loss unit 115 constitute the raw material liquid supply unit, while the pressure reducing valve 131, liquid mass flow controller 132, and vaporizer 133 constitute the raw material vaporization unit. Furthermore, a branch pipe 121 is provided for transferring the raw material liquid 111 from the raw material liquid supply unit to the raw material vaporization unit. The raw material tank 112 stores the raw material liquid 111, and the remaining space is filled with an inert gas. The raw material liquid 111 is a liquid organic siloxane raw material. An example of the organic siloxane raw material is octamethylcyclotetrasiloxane (OMCTS). To prevent excessive dissolution of inert gas in the raw material liquid 111 stored in the raw material tank 112, it is preferable to keep the internal pressure of the raw material tank 112 below 0.1 MPa, and even more preferable to keep it below 0.05 MPa. The circulation piping 113 is a pipeline that starts from the raw material tank 112, circulates outside the raw material tank 112, and returns to the raw material tank 112. A liquid transfer pump 114 and a pressure lo