1. Modification technology of nano calcium carbonate

The modification of nano-calcium carbonate is mainly modified by wet method, which is to add dispersant and surfactant into nano-calcium carbonate slurry, control the particle size and surface activation rate of nano-calcium carbonate through process, and finally obtain the modified nano-calcium carbonate after dehydration, drying, crushing and grading.

At present, the most widely used surfactants with the best effect are mainly organic compounds of fatty acids. One end of the molecule of this kind of compound is carboxyl group, ether group and other polar groups, which can be physically and chemically adsorbed or chemically reacted with the surface of calcium carbonate particles to form a stable bridging structure. The other end of the molecule is a long chain alkyl, similar in structure to polymer molecules, so it has good compatibility with organic polymers. The surface modification of nano-cacO3 can greatly enhance the interface adhesion between nano-cacO3 particles and organic polymer, and effectively reduce the oil absorption value of nano-cacO3, reduce the viscosity of nano-cacO3 / organic polymer system, improve the dispersion and increase the dosage.

2.Influence of nano calcium carbonate on rheological properties of RTV silicone rubber

In practical application, RTV silicone rubber is not only required to have high bond strength and good elasticity, but also needs good construction performance, which can meet the construction requirements of fine surface or groove, tilt or vertical plane. Therefore, the adhesive should not flow, that is, it has thixotropy. Fluid thixotropy refers to the phenomenon that the network structure of fluid changes with shear time at microscopic level and becomes thinning at macroscopic level under the action of external force.

3. To summarize

The application of nano calcium carbonate products in RTV silicone rubber has been very extensive and mature, with the upgrading of silicone rubber industry products, the nano calcium carbonate products also put forward higher and higher requirements. A good nano calcium carbonate product, in addition to the quality must be stable, the indicators of small fluctuations, but also in performance, with high reinforcement, easy to disperse, low thickening, high thixotropy and other characteristics.