Mainly suitable for circuit board (PCB) process; Chemical Industry; Electroplating; Printing and dyeing; Paper making; Medicine; Water-based ink; Ceramic slitting; Cleaning of steel plate; Aluminum processing; Defoaming and defoaming of various sewage treatment and various industrial water systems.


mechanism


one The local surface tension of the foam decreases and the foam bursts


The origin of this mechanism is that high alcohols or vegetable oils are sprinkled on the foam, and when they dissolve into the foam solution, the surface tension there is significantly reduced. Because these substances are generally less soluble to water, the reduction in surface tension is limited to local areas of the foam, while the surface tension around the foam hardly changes. The portion with reduced surface tension is strongly pulled around, extended, and finally ruptured.


2. The defoamer can destroy the elasticity of the membrane and cause the bubble to burst


When the defoamer is added to the foam system, it diffuses to the gas-liquid interface, which makes it difficult for the surfactant with foam stabilization function to restore the elasticity of the membrane.


3. The defoamer can cause the liquid film to drain, thus causing the bubble to burst


The rate of foam drainage can reflect the stability of foam, and the addition of a substance that accelerates foam drainage can also play a role in defoaming.


4. The addition of hydrophobic solid particles can cause the bubble to burst


The hydrophobic solid particles on the surface of the bubble will attract the hydrophobic end of the surfactant, so that the hydrophobic particles produce hydrophilicity and enter the water phase, thus playing the role of defoamization.


5. Solubilizing foaming surfactant can cause bubbles to burst


Some low molecular substances that can be fully mixed with the solution can make the bubble surfactant solubilized and reduce its effective concentration. Low molecular substances with this effect, such as octanol, ethanol, propanol and other alcohols, can not only reduce the surfactant concentration of the surface layer, but also dissolve into the surfactant adsorption layer, reducing the tightness of the surfactant molecules, thus weakening the stability of the foam.


6. The electrolyte disintegrates the surfactant double layer, causing the bubble to burst


For the interaction of the two electric layers of the surfactant with the help of foam to produce a stable foaming solution, the addition of ordinary electrolytes can disintegrate the double electric layer of the surfactant to act as a defoamer.








Make up


(1) Active ingredients


Function: bubble breaking, defoaming, reduce surface tension:


Representatives: silicone oil, polyethers, high alcohols, mineral oil, vegetable oil, etc. [2]


(2) Emulsifier


Function: Disperse the active ingredients into small particles, easy to disperse in water, better play the anti-foam, anti-foam effect.


Representatives: nonyl (octyl) phenol polyoxyethylene ether, soap salt, op series, Twain series, Pan series, etc.


(3) Carrier


Function: helps to combine the carrier and the foaming system, easy to disperse into the foaming system, combine the two, its own surface tension is low, helps to suppress the foam, and can reduce the cost.


Representative: solvents other than water, such as aliphatic hydrocarbons, aromatic hydrocarbons, oxygen-containing solvents, etc


(4) Emulsifying additives


Function: Make the emulsification effect better.


Representative: * Dispersant: hydrophobic silica, etc. * Tackifier: CMC, polyethylene ether, etc.






Select


The selection of defoamer should meet the following points:


1, insoluble or insoluble in the foaming liquid


In order to burst the foam, the defoamer should be concentrated and concentrated on the bubble film. For the case of defoaming agent, it should be concentrated and concentrated in an instant, and for the case of defoaming agent, it should always be maintained in this state. Therefore, the defoamer is supersaturated in the foaming solution, and only insoluble or insoluble is easy to achieve supersaturation. Insoluble or insoluble, it is easy to gather at the gas-liquid interface, it is easy to concentrate on the bubble film, and it can play a role at a lower concentration. For the defoamer used in water systems, the molecules of the active ingredients must be strong hydrophobic and weak hydrophilic, and the HLB value should be in the range of 1.5-3 for the best effect.


2, the surface tension is lower than the foaming liquid.


Only when the intermolecular force of the defoamer is small and the surface tension is lower than that of the foaming solution, the defoamer particles can be immersed and expanded on the foam 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. It has a certain degree of affinity with foaming liquid.


Since the defoaming process is actually a competition between the speed of foam collapse and the speed of foam formation, the defoaming agent must be able to disperse quickly in the foaming solution in order to quickly play a wider range of roles in the foaming solution. In order to make the defoamer diffusion faster, the active ingredient of the defoamer must have a certain degree of affinity with the foaming solution. The active ingredient of defoamer is too close to the foaming solution and will dissolve. Too sparse and difficult to disperse. The effectiveness is good only when the intimacy is right.


4, no chemical reaction with foaming liquid.


The defoamer reacts with the foaming solution, on the one hand, the defoamer will lose its effect, on the other hand, harmful substances may be produced, affecting the growth of microorganisms.


5, small volatility, long action time.


First of all, it is necessary to determine the system that needs to use defoamer, whether it is a water-based system or an oil-based system. If the fermentation industry, it is necessary to use oil-based defoamer, such as polyether modified silicon or polyether. Water-based coating industry must use water-based defoamer, silicone defoamer. Select the defoamer, compare the added amount, and get the most suitable and economical defoamer product at the reference price.