The silicone emulsion type defoamer

The silicone emulsion type defoamer manufacturing process is divided into 3 steps:

• The preparation of a silicone paste. A certain amount of polydimethylsiloxane (hereinafter referred to as silicone oil) having different viscosity, activated silica, modifier and catalyst are stirred and reacted at 120 to 210 ° C for 2 to 4 hours, and after cooling, the main defoaming component is obtained. Formulated silicone paste. The emulsifier is added to dissolve in the oil phase, and the mixture is heated and stirred uniformly, that is, the self-emulsified defoamer compound is obtained. The selection and ratio of the main antifoam component polysiloxane, silica, modifier and catalyst are the key to the performance of the silicone emulsion defoamer.
• Preparation of the initial emulsion. The emulsifier is dissolved in the oil phase, the thickener is dissolved in water, and the phase inversion method is carried out by adding water to the oil to control the emulsification temperature, time and stirring speed, and the initial emulsion is obtained after cooling.The emulsifier is dissolved in the oil phase, and the aqueous phase is added to the oil phase in the order of addition to obtain an emulsion having uniform particles and stable quality. Polysiloxanes are difficult to emulsify, so the correct choice of emulsifier is the key to emulsification. The chemical structure of the Span and Tween surfactants is similar to that of the emulsified dimethyl silicone oil, and the combination effect is good.
• Compounding operation. Under stirring, an antifoaming agent, a foam suppressing synergist and an aqueous solution of a thickener are added. The preservative is emulsified in a primary emulsion by a high shear emulsifier for a certain period of time to obtain a product.Commonly used thickeners are polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, hydroxy cellulose and acrylic polymers, each having its own advantages and disadvantages, and should be selected for different emulsifying systems and application environments.

At present, several technical difficulties in the development of silicone emulsion defoamers are: the development of quick-breaking, anti-foaming and long-lasting silicone paste; the design and synthesis of low-foaming, non-foaming emulsion systems, especially modified silyl ether emulsifiers. Selection; emulsion particle size and stability control; high temperature, alkali resistant, easy to disperse emulsion system development.

Amber Zhang Ms.

Foreign trade 

Zhejiang Ruico Advanced Materials Co., Ltd. (Stock No.873233)

Add: No.188, Liangshan Road, Linghu Town, Nanxun District, Huzhou City, Zhejiang Province, China 313018

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