Method for producing silica particles, synthetic quartz powder and synthetic quartz glass

Abstract

A method for producing silica particles comprising freezing a hydrous silica gel, thawing the frozen gel and removing the water having been separated from the gel by thawing, to thereby dehydrate the hydrous silica gel and provide silica particles; a method for producing a synthetic quartz powder comprising washing and then burning the above silica particles; a method for producing a synthetic quartz powder comprising removing alkaline components from water glass, adding an oxidizing agent and an acid, passing the resultant mixture through a proton type cation exchange resin, and then gelating the resultant solution, followed by washing and firing; and a method for producing a quartz glass comprising holding a silica at 150 to 400 DEG C, 500 to 700 DEG C, and then 1100 to 1300 DEG C, for specific times, respectively.

Description

technical field [0001] The present invention relates to a method for dehydrating hydrous silica gel, and a method for producing synthetic quartz glass powder using the dehydration method, and particularly relates to high-purity glass powder used as raw materials for heat treatment parts for semiconductors, crucibles for pulling semiconductor single crystals, optical parts, etc. Method for producing synthetic quartz glass powder. [0002] In addition, the present invention relates to a method for producing high-purity synthetic quartz powder, and particularly relates to heat treatment components for semiconductors, crucibles for pulling semiconductor single crystals, optical components, quartz lamps, core materials, tooling molds, washing tank materials, etc. The production method of high-purity synthetic quartz powder used as raw material. [0003] Furthermore, the present invention relates to a method for producing quartz glass, in particular, a method for producing high-pur...

AI Technical Summary

Problems solved by technology

[0011] However, these silicas contain a relatively large amount of OH groups (silanol groups), which cannot be sufficiently reduced even by roasting.

When quartz glass obtained from silica containing such silanol groups is used as a raw material, for example, in the manufacture of crucibles for pulling semiconductor single crystals, etc., there are industrial and practical problems such as generation of bubbles during melting or lowering of viscosity.

[0012] Therefore, as a method for removing silanol groups from silica particles, JP-A No. 8-26741 discloses a diffusion technique using silanols in dehumidified air at 1220° C. for 50 hours. However, This method not only lacks industrial applicability in terms of cost due to long-time heat treatment, but also has problems such as devitrification (crystallization) of silica particles

[0013] In addition, Japanese Patent Laid-Open No. 2-289416 discloses a method of temporarily holding at 600 to 1000° C. for a period of time for desiliconization, but in order to sufficiently reduce the content of silanol groups, long-term firing is required.