How to reduce the oil absorption value of silica powder in actual production?
Adding silica powder filler to the polymer base can not only reduce the cost of polymer materials, but also improve the dimensional stability of the material, and impart special physical properties such as compression resistance, impact resistance, corrosion resistance, flame retardancy and insulation. Chemical properties. How to improve the fluidity of silica powder in high polymer, reduce its viscosity, and increase the overall filling rate has been a hot research direction in the industry, and these properties of silica powder depend largely on the oil absorption value.
The oil absorption value is also called the resin adsorption amount, which is an index indicating the amount of absorption of the resin by the silica powder. In practical applications, silica powder uses the oil absorption value as an indicator to roughly predict the amount of resin required for the resin. When the oil absorption value is different, the particle size, specific surface area, dispersibility, wetting degree and adsorption performance of the silica powder are different, thereby affecting the compatibility of the silica powder and the high polymer, so the oil absorption value directly affects the material quality, performance and use.
The oil absorption value is related to the size and shape of the silica powder, the degree of dispersion and cohesion, the specific surface area and the surface properties of the particles. However, since silica powder is mainly used as a filler in related industries, the particle size is highly demanded, so the method of reducing the specific surface area by reducing the particle diameter and lowering the oil absorption value has certain limitations. Therefore, as can be seen from Fig. 1, how to reduce the oil (resin) of the surface and voids of the silica powder particles is the key to lowering the oil absorption value.
It can be seen from Table 1 that the average particle size of the silica powder samples obtained by the ball mill, the vibration mill and the jet mill has little difference, so it can be considered that the oil absorption values caused by the particle size do not change much. However, the results of the oil absorption test of the three are: airflow mill>ball mill>vibration mill, mainly the vibration milled silica powder sample has a good distribution of coarse and fine powder in the whole system, and the fine particles are better filled between the coarse particles and the larger. The filling of the entire system reduces the amount of oil distributed in the voids of the particles, thereby reducing the overall oil absorption of the system.
It can be seen from Table 2 that the vibrating milled silica powder sample has the highest tap density, and further verifying that the good particle size distribution can effectively reduce the void ratio between the powder and improve the powder filling property.
2. Effect of modifier on oil absorption value of silica powder
Figure 3 is a photograph of a silica powder modified with an average particle size of 20um ± 0.5um silica powder, aluminoate modifier modified silica powder modified by a silane coupling agent under an electron microscope, and it can be seen from the figure that the silica powder The dispersibility is determined by the silane coupling agent modified silica powder > aluminate modifier modified silica powder > average particle size of 20um ± 0.5um silica powder.
Table 4 shows the comparison of the oil absorption values ??of the silica powder modified by the silica powder modified by the average particle size of 20um±0.5um silica powder, the aluminate modifier, and the silane coupling agent: the average particle size is 20um±0.5um silica powder>Silica powder modified by aluminate modifier>Silica powder modified by silane coupling agent.
(1) The filling property of silica powder produced by vibrating mill grading system is higher than that of jet mill and ball mill, so its oil absorption value is the lowest.
(2) The modifier has a significant effect on the oil absorption value of the powder, and the silane coupling agent has the best effect on the modification of the silica powder. In the actual production process, different silane coupling agents need to be selected according to different industry needs.