Silicon dioxide with high oil absorption value and low specific surface area and preparation method thereof

Abstract

The invention provides silicon dioxide with a high oil absorption value and a low specific surface area and a preparation method thereof, and the preparation method comprises the following steps: S1, adding water into water glass, dissolving and aging to obtain a water glass solution, and preparing the water glass solution into a sodium silicate solution; preparing a sulfuric acid solution; s2, adding water into a reaction tank, heating, adding a sulfuric acid solution while stirring, dropwise adding a sodium silicate solution and the sulfuric acid solution at the same time, and controlling the pH in the reaction process; s3, tetraethoxysilane is added, then a sodium silicate solution and a sulfuric acid solution are dropwise added at the same time, when the reaction pH value reaches 8.0-9.0, dropwise adding is stopped, and stirring and curing are conducted; s4, dropwise adding a sodium silicate solution and a sulfuric acid solution at the same time; s5, dropwise adding a sulfuric acid solution, adjusting the pH value at the end point, and stirring and aging; and S6, carrying out filter pressing and washing on the formed silicon dioxide, and then carrying out spray drying treatment to obtain the silicon dioxide. The oil absorption value of the silicon dioxide is greater than or equal to 300g / 100g, and the specific surface area is 100-200m < 2 > / g.

Description

technical field [0001] The invention belongs to the technical field of silicon dioxide, and in particular relates to silicon dioxide with high oil absorption value and low specific surface area and a preparation method thereof. Background technique [0002] Silica is rich in micropores and mesopores, and is an amorphous porous structure, which can be used as a carrier for pharmaceutical products. With the cross-infiltration and integrated development of nanotechnology in the silica industry, special functional and special nano-silica has developed rapidly. According to the different physical and chemical properties of silica, it can be used as reinforcing filler for light-colored rubber, opening agent for plastics, matting agent for coatings, resin compounding agent, chemical absorbent, filler for manufacturing, coating agent for special paper, etc. Silicon dioxide is used in food as a glidant and adsorbent, etc. As nano-silica used as powder, the oil absorption value is t...

AI Technical Summary

Problems solved by technology

[0003] At present, the specific surface area of ​​silica is not limited in the relevant standards. The higher the specific surface area of ​​silica, the richer its pore structure, and as time goes by, silica will agglomerate, which will make the product viscosity It is getting bigger and bigger. When the viscosity is too high, it will affect the normal use of the product. Therefore, it is necessary to reduce the specific surface area of ​​silica. The specific surface area of ​​silica is low, which can reduce agglomeration and improve flow-aid ability.

[0004] At present, silicon dioxide is mainly produced by gas-phase method and precipitation method. The silicon dioxide produced by gas-phase method has high oil absorption value but high cost, while the price of silica prepared by precipitation method is relatively low, which is suitable for large-scale use.

Precipitation method is divided into ordinary precipitation method and gel method. The silica oil absorption value obtained by ordinary precipitation method is low (less than 250g / 100g (linseed oil)); the silica oil absorption value obtained by gel method is high (greater than or equal to 300g / 100g (linseed oil)), but the specific surface area is large (500~700m 2 / g), the large specific surface area makes the sample agglomerate seriously and cannot be applied in food