Properties of Silicon Dioxide Matting Agents-Particle size

The average particle size of silica and its particle size distribution play an important role in the reduction of gloss of a coating. For a given coating and film thickness, the best matting effect is achieved at the optimum particle size distribution. The narrower the particle size distribution, the better.

A wide range of particle size distribution indicates a large number of “fine” and “coarse” particles. In addition to the poor matting effect, the “fine” particles will increase the viscosity of the coating; the “coarse” particles will make the surface of the coating film excessively rough. Generally, the average particle size between 8-10um silica matting powder, more suitable for thicker coating film architectural coatings. The larger particle size of silica is easier to disperse and has little effect on the viscosity of the coating system.

The binding of polymerizable surfactants on the surface of latex particles increases with the amount of surfactants, but decreases with the increase of the inhibitor (sodium persulfate) concentration .

The rate of polymerization increases with Trem LF-40 The decrease in concentration accelerates. This is contrary to the performance of ordinary surfactants in emulsion polymerization, and usually the rate increases with increasing concentration. Increasing the initial concentration of polymerizable succinate sulfonate can produce fine-particle emulsions [271. It can be found that Trem LF-40 has quite strong chain transfer and ptfe wax lubricant the reaction between water and the latex particle interface, which is a polymerizable surfactant and a non-polymerizable surfactant. There is a significant difference in polymerized surfactants .

Using traditional surfactants such as SDS and this reactive emulsifier to make polystyrene films to measure the contact angle of water, it can be clearly found that the reactive emulsification The contact angle of the polystyrene prepared by the agent is much larger than that of the non-reactive surfactant [261.

In order to better control the polymer, we have tried to prepare vinyl acetate and vinyl 2- by microemulsion polymerization. Copolymer of ethylhexyl ester. It can be found that, compared with traditional emulsifiers, the reaction rate of microemulsion polymerization is greatly improved, but the number of latex particles is reduced: 29. This is mainly affected by reactive surfactants.