Performance requirements for defoamer in mortar products
1.Overall requirements for mortar defoamer
mortar defoamer should have antifoaming effect, no serious side effects, stable storage, easy to release active ingredients, economic, meet the requirements of environmental protection.
2. Requirements for active ingredients of defoaming agents
1) insoluble in the foaming solution: most excellent antifoaming agents are insoluble in the foaming solution, especially for the antifoaming effect, the antifoam must be supersaturated in the foaming solution, and the HLB value of the defoamer in the water-based system is 1.5~3.
2) The surface tension is lower than the foaming liquid: only when the intermolecular force of the defoamer chemical is small and the surface tension is lower than the foaming liquid, the antifoam particles can be immersed and expanded on the bubble film. It is worth noting that the surface tension of the foaming solution is not the surface tension of the solution, but the surface tension of the foaming solution.
3) The defoamer chemical has a certain affinity with the foaming liquid, and the defoamer can be rapidly dispersed: because the defoaming process is actually the competition between the foam collapse speed and the foam generation speed, the defoaming agent must be able to rapidly disperse in the foaming liquid, so as to play a role in a wider range of foaming liquid. In order to make the defoaming agent diffuse faster, the active component of the antifoam must have a certain degree of affinity with the foaming liquid. The active ingredient of the defoamer is too close to the foaming liquid and will dissolve; Too thin and difficult to disperse. Only the effect of antifoaming agent will be good.
4) There is no chemical reaction between defoamer and foaming solution: if the defoaming agent reacts with foaming solution, on the one hand, the defoaming agent will lose its effect, and on the other hand, harmful substances may be produced to affect the growth of microorganisms.
5) The volatility of the antifoam agent is small: first of all, it is necessary to determine the system that needs to use the defoamer, which is the water-based system or the oily system. For example, in the fermentation industry, oil-based antifoaming agents should be used, such as polyether modified silicon or polyether. Water-based coating industry will use water-based defoaming agent, silicone defoamer.
6) Less dense than the foaming liquid phase (because the foam generally accumulates at the liquid level);
7) Antifoaming agent is non-toxic and harmless to the environment;
8) Defoamer resistant to high temperature and low temperature;
9) Antifoaming agent is not easy to adhere to the wall;
10) Small amount of addition.
