What's the reason of oil have foam? It can be divided into two aspects, one is surface foaming, it can be controlled by Anti-foaming Agent, the other is the foam inside the oil, the internal foam is not easy to be improved by Antifoam Additive, and the effective anti-foaming agent for surface foam may make the internal foam more stable. For oil with excellent defoaming performance, Base Oil and Lubricant Additive should be mixed. The mechanism of antifoaming additive is complex, and the representative views include reducing partial surface tension, expanding and permeating.
1. Reduce surface tension
This mechanism is achieved by reducing the surface tension. This view holds that the surface tension of the antifoam additive is smaller than that of the foaming liquid. When the anti-foaming agent is in contact with the foam film, the surface tension of the bubble film decreases locally and the rest remains unchanged. However, this mechanism is limited to local positions, because this material can't solved in water, so the diffusion force is poor, which does not play much role in the surrounding foam. When the tension of the foam surface decreases, under the action of this force, slowly spread around, and finally form a rupture.
2. Expansion
This view holds that the anti-foaming agent drop invade the bubble membrane and make it a part of the membrane, and then expand on the membrane, which can effectively inhibit the diffusion of the active agent and make it difficult to exert its elastic ability, thus eliminating the surface foam.
3. Penetration
This view holds that the function of antifoaming agent is to increase the permeability of bubble wall to air, thus accelerate the merger of foam, reduce the strength and elasticity of bubble wall, and achieve the purpose of breaking bubble.
