Advantages and disadvantages of the same type of defoamer
- 2023-09-01 17:36:28
- admin
Advantages and disadvantages of the same type of defoamer
Organic defoamer such as mineral oils, amides, low alcohols, fatty acids, fatty acid esters and phosphate esters has been studied and applied earlier, belonging to the first generation of defoamer, which has the advantages of easy access to raw materials, high environmental performance and low production cost.The disadvantages are low defoaming efficiency, strong specificity and harsh use conditions.
Polyether defoamer is the second generation of defoamer, which mainly includes straight chain polyether, polyether with alcohol or ammonia as the starting agent and polyether derivatives with end group esterification.The biggest advantage of polyether defoamer is its strong anti-foam ability. In addition, some polyether defoamer has excellent properties such as high temperature resistance, strong acid and alkali resistance.The disadvantages are that the use conditions are limited by temperature, the use field is narrow, the defoaming ability is poor, and the bubble breaking rate is low.
Silicone defoamer (the third generation of defoamer) has the advantages of strong defoamer performance, rapid defoamer ability, low volatility, no toxicity to the environment, no physiological inertia, wide range of use, etc., so it has broad application prospects and huge market potential, but the foam suppression performance is poor.
Polyether modified polysiloxane defoamer has the advantages of polyether defoamer and silicone defoamer at the same time, which is the development direction of defoamer.Sometimes it can also be reused according to its reverse solubility, but at present, there are fewer types of such defoamer, which is still in the research and development stage, and the production cost is high.
Selection of defoamer
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
The addition of the stock solution and the addition after dilution have some deviations to a certain extent, and the proportion is not equal. Due to the low surfactant concentration, diluted defoamer emulsions are extremely unstable, will not stratify quickly and have relatively poor defoamer performance, and are not suitable for long-term storage.
The proportion of defoamer added needs to be verified by field tests, and should not be added excessively.
The amount of defoamer
There are many types of defoamer, and the amount of addition required for different types of defoamer is different. Here we introduce the amount of six types of defoamer:
1.Alcohol defoamer: When alcohol defoamer is used, the dosage is generally within 0.01-0.10%.
2.Oil defoamer: the addition amount of oil defoamer is between 0.05-2%, and the addition amount of fatty acid ester defoamer is between 0.002-0.2%.
3.Amide defoamer: amide defoamer effect is better, the amount of addition is generally within 0.002-0.005%.
4. Phosphoic acid defoamer: phosphoic acid defoamer is most commonly used in fibers and lubricating oil, the amount of addition is between 0.025-0.25%.
5. Amine defoamer: amine defoamer is mainly used in fiber processing, the addition amount is 0.02-2%.
6. Ether defoamer: ether defoamer is used more in paper printing and dyeing and cleaning, and the addition amount is generally 0.025-0.25%.
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