1. Analysis of main components of polyether silicone oil defoamer compound 　

Polyether modified silicone oil has strong emulsification ability, can emulsify silicone oil and self-emulsify, make the entire emulsification system very stable; due to the low surface tension of polysiloxane and the easy dispersibility of polyether, it can eliminate The foaming agent is easy to disperse and spread; when the temperature is higher than the cloud point, it has defoaming property, and the temperature below the cloud point is dispersed in the foaming liquid to make the defoaming lasting. Polyether silicone oil also has excellent high and low temperature resistance, acid and alkali resistance, anti-aging, electrical insulation, flexibility, safety and environmental protection, stable storage and convenient use. It is a defoamer with excellent performance and wide application prospects. .

2. The effect of the amount of polyether silicone oil on the performance of defoamer 　　

Polyether silicone oil itself has defoaming and anti-foaming properties, and can also have a synergistic effect with methyl silicone oil/modified silica. The study found that: within a certain dosage range, as the amount of polyether silicone oil added increases, the defoaming time becomes shorter and the foam suppression time is prolonged. This is due to the self-emulsifying ability of polyether silicone oil, which increases the stability of the emulsion and its dispersibility in water, and can play a synergistic effect between the components, thereby significantly improving the defoaming effect of the defoamer. 　　

3. The effect of methyl silicone oil viscosity and dosage on the performance of defoamer 　　

Dimethicone is also a common main component of defoamers. The general rule of its dosage and applicable viscosity is: the lower the viscosity of the foaming liquid, the higher the viscosity of the selected silicone oil, and the higher the viscosity of the methyl silicone oil, the less solubility and foam suppression It takes a long time, but it is difficult to emulsify; on the contrary, the higher the viscosity of the foaming liquid, the lower the viscosity of the selected silicone oil, which is easy to disperse in the foaming liquid for defoaming, but the solubility is large and the foam suppression time is short. The content of methyl silicone oil in the emulsion should also be moderate. If the amount is too low, the defoaming effect will be poor; if the amount is too high, it will not be easy to emulsify. The defoamer with low solubility can inhibit foam generation for a long time and continue to kill the foam system.　　

4. The influence of silicon dioxide selection and dosage on the performance of defoamer 　　

Fumed silica (white carbon black) has a large specific surface area, low density, easy to disperse, without hydrophobic treatment, it is hydrophilic, and it is difficult to infiltrate and disperse in the organic phase; after hydrophobic treatment, the surface hydroxyl content is reduced and the aggregation tendency Attenuation, the surface free energy is reduced, the hydrophilicity is changed to hydrophobic, and the wettability and dispersibility with the organic phase are improved. Fumed white carbon black is commonly used to enhance the dispersion ability of silicone oil in foaming systems and increase the stability of emulsions. The most suitable amount of white carbon black in the defoamer should be about 1.3%.　　

5. The influence of emulsifier selection and dosage on the performance of defoamer 　　

To form a stable emulsion, a suitable emulsification system must be selected. First, consider that the HLB value of the emulsifier is close to the HLB value of silicone oil (approximately 8-11), and secondly, consider that the foaming power of the emulsifier is small. The affinity between the emulsified system and the hydrophobic base of the emulsifier should be considered. The closer the structure, the better the emulsification effect. Span and Tween emulsifiers have a chemical structure similar to that of silicone oil, and are widely used in the emulsification of silicone oil. The amount of emulsifier should also be particulary. If the amount is too large, although the stability is improved, the emulsion will be too viscous and the defoaming effect will decrease; if the amount is too small, the emulsion will be unstable and easy to layer. When selecting emulsifiers, several emulsifiers with a certain difference in HLB are generally used for compounding, and the effect is better than using a single emulsifier.　　

6. Research progress of polyether modified silicone defoamer 　　

Xie Wenfeng and others synthesized a stable emulsion type silicone defoamer SXP-3 with polydimethyl silicone oil, modified silicone oil and white carbon black as the main components. It has fast spreading, uniform dispersion, non-volatile, high chemical stability, High temperature resistance, acid and alkali resistance, wide application range, low dosage and high efficiency. Li Adan used polydimethylsiloxane and polyether (glycerol polyoxyethylene polyoxypropylene ether) to make modified silicone oil; Cai Zhenyun’s research group used allyl alcohol polyether for polyethers of different structures, molecular weights and different viscosities. The hydrogen content silicone oil graft modification has been systematically studied, and different polyether silicone oil structures with good defoaming and anti-foaming effects have been obtained, and their compounding and performance studies have been carried out; Wu Fei and Cao Zhiping invented An efficient, safe, and inexpensive silicone defoamer for water-based flexographic inks and water-based coatings and its compounding process; An Qiufeng et al. based on the synthesis of amino-modified silicone oil, The addition reaction of silicone oil was preliminarily discussed. Zhang Baoyin et al. used polyether 5010 as the main raw material and synthesized polyether silicone oil compound defoaming agent under the conditions of the special emulsifier for GR-03. Compared with the original silicone emulsion, its defoaming ability was nearly doubled.　　

With the continuous discovery of new high-activity defoaming components, the research on the synergistic effect of compound components is intensified. In order to maximize the strengths and avoid weaknesses, and give full play to the advantages of various defoamers, the defoamers will move towards high efficiency, durability and performance. The new high-efficiency, multi-functional composite silicone polyether defoaming agent with strong development and synthesis applicability, small dosage, and improving product quality and equipment utilization will be the current development direction of defoamers. At the same time, the continuous development and discovery of new fields also provides a broad market prospect for the development of new high-efficiency and multifunctional composite silicone polyether defoamers. For example, in the food industry, it is used to defoam in various concentration, fermentation, and distillation processes; in medicine, it is usually used to remove flatulence from organs or internal organs in the stomach before surgery, light and gastroscopy; In the production of personal protective equipment, the use of polyether-modified silicone oil has both self-emulsification, surface activity and physiological inertness. It can be colorless, odorless, non-irritating to the human body and does not affect the normal breathing of the skin. , Antistatic and anti-bacterial hair care products.