Method for preparing core-shell silicon dioxide coated nano calcium carbonate

Abstract

The invention provides a preparation method for core-shell type silicon dioxide-coated nanometer calcium carbonate, which comprises following steps: adding silicate in calcium carbonate suspension pulp; stirring and mixing using emulsion pump; introducing kiln gas with CO2 for carbonization until the pH is 6.5 to 7.0; heating to 60 to 90 DEG C; adding coating agent for coating treatment; the product is obtained after the coated pulp is filtered and the filter cake is dried. The preparation method for core-shell type silicon dioxide-coated nanometer calcium carbonate has the advantages of improving the acid resistance of nanometer calcium carbonate since silica sol precipitated through hydrolysis is coated on the surface of nanometer calcium carbonate, improving dispersion of the product in polymer due to surface treatment using coupling agent and organic acid, good acid resistance and dispersion, greatly improving physical and chemical properties, and felicitating industrial production with simple operation.

Description

technical field [0001] The invention relates to a preparation method of calcium carbonate, in particular to a preparation method of core-shell silica-coated nano-calcium carbonate. Background technique [0002] As a functional filler, nano-active calcium carbonate is widely used in coatings, rubber, plastics and other industries. Its main purpose is to improve the comprehensive performance of products and reduce production costs. [0003] However, there are many problems in the actual application of nano-active calcium carbonate: [0004] First, due to the surface characteristics of calcium carbonate, stearic acid treatment is the most effective surface treatment, and the singleness of the surface treatment agent restricts the expansion of the application field; [0005] The second is that the products treated with stearic acid have poor dispersion and serious agglomeration when used in silicone rubber, and the advantages of nano-powders are not fully utilized; [0006] Th...

AI Technical Summary

Problems solved by technology

[0004] First, due to the surface characteristics of calcium carbonate, stearic acid treatment is the most effective surface treatment, and the singleness of the surface treatment agent restricts the expansion of the application field;

[0005] The second is that the products treated with stearic acid have poor dispersion and serious agglomeration when used in silicone rubber, and the advantages of nano-powders are not fully utilized;

[0006] The third is due to the fact that calcium carbonate itself will decompose and release carbon dioxide in a slightly acidic medium, which restricts its scope of use.

[0008] Chinese patent, 02115028.1 introduces a preparation method in which sodium silicate is added to calcium carbonate slurry and ultrasonically dispersed, and then dilute sulfuric acid solution is added to form a silicon dioxide-coated calcium carbonate surface under strong stirring. The method uses ultrasonic Dispersion is difficult to achieve in large-scale industrial production. At the same time, the addition of strong acidic sulfuric acid can easily make the calcium carbonate slurry partially acidic and dissolve, which is not conducive to industrial production.

This method is not only complicated in process, but also the production cost of silica sol prepared by ion exchange method is high, and the product lacks comprehensive competitiveness.

There is no report of industrialized production in the above patents