阅读说明：本技术 一种制备大粒径硅溶胶的方法 (Method for preparing large-particle-size silica sol ) 是由 王军强 于 2020-06-12 设计创作，主要内容包括：本发明公开了一种制备大粒径硅溶胶的方法,包括以下步骤：将浓度为10wt％的晶种溶液加入反应釜,加入碱溶液使得溶液pH值控制在11.2至11.8,将温度控制在100-120℃,加热25至30h后,当pH值小于10.3时,加入碱溶液并将pH控制维持在9.8至10.3,直到得到粒径为100-120nm的硅溶胶溶液,同时通入浓度为10wt％的晶种溶液使得液面维持不变。硅溶胶合成过程中pH值的控制,对合成后的硅溶胶的抛光速率影响至关重要,将pH值控制在9.8-10.3时,其抛光速率比不控制pH的工艺提高22.3％,抛光速率比pH控制在9.3-9.8的工艺提高34.5％,因此,控制pH在9.8-10.3能有效提高其抛光速率。(The invention discloses a method for preparing large-particle-size silica sol, which comprises the following steps of: adding a seed crystal solution with the concentration of 10 wt% into a reaction kettle, adding an alkali solution to control the pH value of the solution to be 11.2-11.8, controlling the temperature to be 100-120 ℃, heating for 25-30 h, adding the alkali solution and controlling the pH value to be 9.8-10.3 when the pH value is less than 10.3 until a silica sol solution with the particle size of 100-120nm is obtained, and simultaneously introducing the seed crystal solution with the concentration of 10 wt% to keep the liquid level unchanged. The pH value is controlled in the process of synthesizing the silica sol, the influence on the polishing rate of the synthesized silica sol is crucial, when the pH value is controlled to be 9.8-10.3, the polishing rate is improved by 22.3 percent compared with the process without controlling the pH value, and the polishing rate is improved by 34.5 percent compared with the process with controlling the pH value to be 9.3-9.8, so that the polishing rate can be effectively improved by controlling the pH value to be 9.8-10.3.)

1. A method for preparing large-particle-size silica sol, which is characterized by comprising the following steps:

adding a seed crystal solution with the concentration of 10 wt% into a reaction kettle, adding an alkali solution to control the pH value of the solution to be 11.2-11.8, controlling the temperature to be 100-120 ℃, heating for 25-30 h, adding the alkali solution and controlling the pH value to be 9.8-10.3 when the pH value is less than 10.3 until a silica sol solution with the particle size of 100-120nm is obtained, and simultaneously introducing the seed crystal solution with the concentration of 10 wt% to keep the liquid level unchanged.

2. The method for preparing large-particle size silica sol according to claim 1, wherein the silica sol solution has a solid content of 35 to 45%.

3. The method for preparing large particle size silica sol according to claim 1, wherein said seed solution is obtained by the steps of:

adding active silicic acid into a reaction kettle, adding an alkali solution to control the pH value of the solution to be 9-11, adding a calcium chloride solution with the concentration of 1-3 g/L into the reaction kettle, heating to 100-120 ℃, continuously adding the active silicic acid into the solution when water vapor begins to evaporate, and keeping the liquid level of the active silicic acid constant until a seed crystal solution with the particle size of 20-30 nm is obtained.

4. The method of claim 2, wherein the concentration of the active silicic acid is 3% to 5%.

5. The method of any one of claims 1 to 4, wherein the alkali solution is KOH or NaOH.

6. The method for preparing large-particle size silica sol according to any one of claims 1 to 4, wherein the heating is steam heating.

Technical Field

The invention relates to the technical field of fine polishing, in particular to a method for preparing large-particle-size silica sol.

Background

Currently, polishing solution products mainly use monodisperse silicon oxide as an abrasive, and the traditional silicon oxide abrasives have two types: sintered silica and colloidal silica. The sintered silicon oxide has high polishing rate but the polished material has poor surface quality and serious scratch; the colloidal silica surface has good quality but a slow polishing rate. How to increase the polishing rate of the colloidal silica is a big problem faced by the CMP polishing solution.

Disclosure of Invention

It is an object of the present invention to provide a method for preparing a large particle size silica sol which solves one or more of the above-mentioned problems of the prior art.

The invention provides a method for preparing large-particle-size silica sol, which comprises the following steps of:

adding a seed crystal solution with the concentration of 10 wt% into a reaction kettle, adding an alkali solution to control the pH value of the solution to be 11.2-11.8, controlling the temperature to be 100-120 ℃, heating for 25-30 h, adding the alkali solution and controlling the pH value to be 9.8-10.3 when the pH value is less than 10.3 until a silica sol solution with the particle size of 100-120nm is obtained, and simultaneously introducing the seed crystal solution with the concentration of 10 wt% to keep the liquid level unchanged.

In some embodiments, the silica sol solution has a solids content of 35% to 45%.

In some embodiments, the seed solution is obtained by:

adding active silicic acid into a reaction kettle, adding an alkali solution to control the pH value of the solution to be 9-11, adding a calcium chloride solution with the concentration of 1-3 g/L into the reaction kettle, heating to 100-120 ℃, continuously adding the active silicic acid into the solution when water vapor begins to evaporate, and keeping the liquid level of the active silicic acid constant until a seed crystal solution with the particle size of 20-30 nm is obtained.

In some embodiments, the concentration of active silicic acid is 3% to 5%.

In some embodiments, the alkali solution is KOH or NaOH.

In some embodiments, the heating means is steam heating.

Drawings

FIG. 1 is a graph showing changes in pH in example 1;

FIG. 2 is a graph showing changes in pH values of comparative example 1;

FIG. 3 is a graph showing changes in pH values of comparative example 2;

FIG. 4 is a graph showing changes in pH values of comparative example 3;

FIG. 5 is a statistical graph of the polishing rates of example 1 and comparative examples 1 and 2.

Detailed Description

The present invention will be described in further detail below with reference to embodiments.