Silicon dioxide solution preparation method, grinding fluid, and manufacture method of glass substrate

Abstract

The invention provides a silicon dioxide solution preparation method, grinding fluid, and a manufacture method of a glass substrate. The silicon dioxide solution preparation method is a silicon dioxide solution preparation method for removing foreign matters from a silicon dioxide solution containing silicon dioxide particles with a primary particle size of 1-80 nm, wherein the centrifugal acceleration G, the ratio of the sediment distance and the sediment time h / t, and the viscosity [eta] of the solution are controlled, thereby enabling the particle size Dp of the removed foreign matters to be 0.1-1 [mu]m. The grinding fluid is used in grinding of a main plane of the glass substrate for a magnetic recording medium, and contains the silicon dioxide solution prepared by the silicon dioxide solution preparation method enabling the particle size Dp of the removed foreign matters to be 0.1-1 [mu]m. The manufacture method of the glass substrate for the magnetic recording medium includes a procedure of using the grinding fluid to grind the main plane.

Description

technical field [0001] The present invention relates to a method for preparing a silicon dioxide solution, a polishing liquid containing the silicon dioxide solution prepared by the method for preparing the silicon dioxide solution, and a method for manufacturing a glass substrate for a magnetic recording medium using the polishing liquid. Background technique [0002] In recent years, in magnetic recording medium (hereinafter, also referred to as magnetic disk) devices, the increase in recording density has been rapidly advanced. For magnetic disk devices, random access is realized by scanning the magnetic head slightly on a high-speed rotating magnetic disk. In order to take into account high recording density and high-speed access, it is required to reduce the distance between the magnetic disk and the magnetic head (head flying height) and increase The rotational speed of the disk. [0003] For the base material of magnetic disks, aluminum (Al) coated with nickel-phosph...

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Problems solved by technology

[0007] But, in the solution that is used as polishing liquid, contains abrasive grain (such as silicon dioxide particle etc.) in the process of production or preservation, under the situation that foreign matters such as coarse particle are mixed, use this polishing liquid to the main plane of glass substrate. When polishing, there are following problems that adversely affect the quality of the glass substrate for magnetic recording media: microscopic damage occurs on the surface of the glass substrate, and foreign matter adheres to the surface of the glass substrate and remains on the surface of the final product to become Defects, etc.

[0009] However, the method of Patent Document 1 has the following problems: colloidal silica with higher viscosity clogs the filter, and even colloidal silica particles are captured by the filter to reduce the recovery of colloidal silica ( poor yield), etc.

In the methods for removing foreign matter by centrifugation such as Patent Documents 2 and 3, the conditions of centrifugation are not optimized, and the removal of foreign matter is not sufficient.

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