What are the functions of silicone oil in polyurethane foaming?

<font face= "Microsoft Yahei" Silicone oil is a foam stabilizer. Foam stabilizers are a type of surfactant whose main function is to control the cell structure and uniformity.

The specific performance of silicone oil used in foaming is:

1. Reducing surface tension is beneficial to producing uniform microbubbles and stabilizing cells to reduce gas diffusion.

2. Rapidly increasing the viscosity of the material helps slow down the The cells quickly thin and bubble.

3. Increase the strength of the cell membrane wall and cell meridians .

4. Reduce the mixing of impurities to avoid the reduction of local surface tension in the cells Collapse and voids.

5. When the amount of silicone oil is low, the foam with larger pores will not Stablize. Higher dosages result in smaller pore sizes and increased foam surface area. If too much is used, the foam will collapse when it reaches its highest point. The reason is that the bubble wall is too thin and the support strength is insufficient. In addition, the production process of silicone oil is very complex and strict. Different formulas, different processing conditions and production methods make the final products very different. In other words, different silicone oils directly affect the quality of your products, including: appearance, feel, hardness, and tensile strength.

Using too much or too little silicone oil will affect the quality of the foam.

Use a large amount: it will increase the elasticity of the foam wall in the later stage and should not break. The cells are fine. causing obturation.

Low dosage: too little silicone oil is used, and the foam stability is insufficient , severe coalescence occurs, the cells are large and uneven, and even collapse.

In addition to the appropriate dosage of silicone oil to use, more attention should be paid to the selection of appropriately active silicone oil varieties. For different product series, the correct selection of silicone oil varieties is the basis for success. Never use the same silicone oil. One ​​variety of silicone oil meets the production needs of various foams.

Of course, the dosage of silicone oil is also related to other components in the formula, especially the dosage of stannous octoate and the isocyanate index. When producing very low density foam When , the dosage of silicone oil is also increased accordingly.

Finally, from small and pilot experiments to mass production, special attention should be paid to the amount of silicone oil used. Due to stirring during mass production As the speed increases, the amount of silicone oil needs to be appropriately reduced to meet the expected product requirements.