CN-118561285-B - Colloidal silica and method for producing same

Abstract

The present invention aims to provide a colloidal silica containing silica particles having a proper true specific gravity, a high aggregation ratio and a high alkoxy group content in high purity, and a method for producing the colloidal silica with ease and at a low production cost. The present invention relates to a colloidal silica characterized in that the average primary particle diameter of silica particles contained in the colloidal silica is 33nm or more, the aggregation ratio is 1.2 or more, the true specific gravity is 1.95 or more, the proportion of the number of silica particles having a circular equivalent diameter of less than 20nm is less than 15% by mass and the proportion of primary amine having a circular equivalent diameter of 5 mu mol or more is contained in 1g of silica particles per 1g of silica particles.

Inventors

• Negishi yuu
• OTSUKI HIDEKI
• YAMASHITA HIROAKI
• Senman Toshihiro

Assignees

• 扶桑化学工业株式会社

Dates

Publication Date

20260512

Application Date

20200226

Priority Date

20190306

Claims (1)

1. 1. A colloidal silica, characterized in that, The average primary particle diameter of silica particles contained in the colloidal silica is 33nm to 200nm, the aggregation ratio is 1.2 to 5.5, the silanol group density is 1.9/nm 2 to 5.0/nm 2 , Alkoxy groups of 1000 mass ppm to 15000 mass ppm are contained in each 1g of silica particles, The proportion of the number of silica particles having a circular equivalent diameter of less than 20nm is less than 15%.

Description

Colloidal silica and method for producing same The application relates to a divisional application of a patent application with the same name 202080018899.3, which is filed on 26 months in 2020. Technical Field The present invention relates to colloidal silica and a method for producing the same, and more particularly to colloidal silica containing silica particles having an average primary particle diameter of 33nm or more, an aggregation ratio of 1.2 or more, a true specific gravity of 1.95 or more and containing an alkoxy group, and a method for producing the same. Background Colloidal silica is formed by dispersing silica particles in a medium such as water, and is used as a physical property improver in the fields of paper, fiber, steel, etc., and also as an abrasive for electronic materials such as semiconductor wafers. For silica particles dispersed in colloidal silica used in such applications, high true specific gravity and high aggregation are required. As a method for producing colloidal silica capable of satisfying the above-mentioned requirements, for example, a method for adding a hydrolysate obtained by hydrolyzing an alkoxysilane to a mother liquor containing an alkaline catalyst or the like is disclosed (for example, see patent document 1). However, according to the production method described in patent document 1, a hydrolysate obtained by once hydrolyzing an alkoxysilane is prepared, and then the hydrolysate is added to a mother liquor, whereby dense particles having a high true specific gravity can be obtained, but there is a problem that defects (e.g., scratches) on the surface of a substrate or the like as an object to be polished increase due to an excessively high true specific gravity. In addition, the manufacturing process is long and multi-stage, and there are problems such as complexity and high cost. Further, a method for producing colloidal silica by adding an alkoxysilane to a mother liquor without hydrolyzing the alkoxysilane is disclosed (for example, see patent document 2). However, patent document 2 does not describe a method for producing silica particles having a high aggregation ratio and a high true specific gravity, and it is difficult to obtain high polishing properties of the colloidal silica obtained by the production method described in patent document 2, and there is room for further improvement of polishing properties. Accordingly, development of colloidal silica excellent in grindability is desired, and development of a production method capable of easily producing the colloidal silica and reducing production cost is desired. Prior art literature Patent literature Patent document 1 International publication No. 2010/035613 Patent document 2 Japanese patent laid-open publication 2016-008157 Disclosure of Invention Technical problem to be solved by the invention The purpose of the present invention is to provide a colloidal silica containing silica particles having an alkoxy group and a proper true specific gravity, and a production method by which the colloidal silica can be easily produced and the production cost can be reduced. Technical scheme for solving technical problems As a result of intensive studies to achieve the above object, the inventors of the present invention have found that the above object can be achieved by the colloidal silica containing silica particles having an average primary particle diameter of 33nm or more, an aggregation ratio of 1.2 or more and a true specific gravity of 1.95 or more, containing 1000 mass ppm or more of alkoxy groups per 1g of silica particles, a ratio of the number of silica particles having a circular equivalent diameter of less than 20nm of less than 15%, and containing 5. Mu. Mol or more of primary amine per 1g of silica particles. Representative of the invention is as follows. Item 1. A colloidal silica, wherein, The average primary particle diameter of the silica particles contained in the colloidal silica is 33nm or more, the aggregation ratio is 1.2 or more, the true specific gravity is 1.95 or more, The content of alkoxy groups per 1g of silica particles is 1000 mass ppm or more, The proportion of the number of silica particles having a circular equivalent diameter of less than 20nm is less than 15%, The silica particles contain 5. Mu. Mol or more of primary amine per 1g of silica particles. The colloidal silica according to item 1, wherein, The silica particles have a true specific gravity of 1.95 to 2.20. The colloidal silica according to item 1 or 2, wherein, The surface of the silica particles has an organic functional group represented by the following general formula (1). -(CH2)n-R3(1) (In the formula (1), n represents an arbitrary integer of 0 or more, R 3 represents an arbitrary functional group.) item 4. The colloidal silica according to any one of items 1 to 3, wherein, The surface of the silica particles has a cationic organic functional group. The colloidal silica according to item 4, wherein, T