The function of gas-phase matting powder depends on the dispersion strength to a large extent, at least it needs to be dispersed by a high-speed disperser. To achieve the best dispersion effect, rotor-stator dispersion or ball mill, three-roll machine dispersion, etc. can be used. The best choice of dispersing method and dispersing equipment depends on the consistency of the system. It is recommended to disperse all the fumed silica with part of the liquid or part of the formula raw materials, and then add the remaining liquid and other formula raw materials to adjust the content of fumed silica to reach The recipe calls for ratios.
Silicon dioxide selection:
1. Consider the physical and chemical properties of silica, such as particle size distribution and average particle size.
2. According to different resin characteristics, solvent types, and system viscosity, choose the appropriate product.
3. Reasonable selection of precipitated silica and fumed silica. The gas phase method is characterized by good transparency, both haze and blackness, and good color development, and is mostly used in mid-to-high-end products. The precipitation method is characterized by high extinction efficiency, limited transparency, insufficient color development, and the comprehensive blackness and haze efficiency is about 70% of the gas phase method, and it is mostly used for middle and low-end products.
Evaluation method for silica products:
1. Blackness of coating, evaluation of transparency;
2. It is better not to reflect light with naked eyes (or gloss meter), and evaluate haze or extinction
3. Repeatedly observe whether the coating turns white, and evaluate the scratch resistance;
4. The prepared finishing agent should be left to stand for a period of time. It is better if there is no hard sediment. Then evaluate the suspension.
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