Manufacturing method of silica sol and obtained silica sol

Abstract

A process for preparing high-granularity Si sol includes such steps as heating the SiO2 dispersed water, stirring while adding alkaline catalyst and metallic Si powder, hydrolytic reaction at pH=7-14 to obtain active silicic acid micro-particles, and quickly adsorbing the micro-particles by SiO2 seed particles to become target sol. Its advantages are high speed and controllable and uniform granularity.

Description

technical field [0001] The invention relates to a method for producing silica sol and the silica sol prepared therefrom. Background technique [0002] At present, there are generally the following methods for producing large-size silica sol in industry. One is the method of adopting high temperature and high pressure method in the ion exchange process and adding active silicic acid raw materials dropwise while heating and evaporating on the basis of seed liquid. Such as U.S. patents: US3012972 (1962), US4356107 (1982), are to use high temperature and high pressure to process alkaline small particle size silica sol in order to obtain large particle size silica sol; patent US3947376 (1976), US4304575 (1981) and China The patent CN1155514A (1997) basically adopts silicon dioxide with a certain particle size as the seed liquid, and then adopts the method of adding active silicic acid microparticles dropwise while heating and evaporating to obtain a silica sol with a large parti...

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Problems solved by technology

However, there are deficiencies in these processes: the particle size of the silica sol prepared by the high temperature and high pressure method is very limited, and the particle size is not uniform. For example, the preparation of a silica sol with an average particle diameter of about 20 nm requires a pressure of 10 to 15 atmospheres. And the water temperature of nearly 160-180 ℃; and high performance requirements for production equipment, high energy consumption, and a large number of concentration steps in the later stage; the method of adding active silicic acid particles to the seed liquid avoids high temperature and high pressure, and requires high equipment performance. Low, and can prepare silica sol with relatively large particles

However, in these methods of using silica powder as the main raw material to prepare silica sol, the particles of the prepared silica sol are all low, and it is difficult to meet the requirements for preparing higher-grade silica sol, such as silica sol for semiconductor chip polishing, etc.

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