Talking about Methyl High-hydrogen Silicone Oil
Nov 4, 2020
1 Industry status of methyl high-hydrogen silicone oil
Methyl high-hydrogen silicone oil is often referred to as high-hydrogen silicone oil. It is a very important silicone oil product that is very popular at home and abroad. The siloxane main chain in the high-hydrogen silicone oil product contains highly active silicon-hydrogen bonds, which can react with many active groups, and the surface energy of methylsiloxane chain links is low, so its synthetic materials have good properties. Water resistance. Based on this feature, it is often used as a waterproofing agent for materials. At the same time, it can also be used as a crosslinking agent, bridging agent, softening agent, smoothing agent, surfactant, pesticide spreading agent and so on.
2 Preparation of high-hydrogen silicone oil by solvent-free method
Based on the many problems in the process of preparing high-hydrogen silicone oil by solvent method, the method of preparing high-hydrogen silicone oil by solvent-free method has been more and more used in recent years. This method is also prepared by the MH.M3 co-hydrolysis method, but the physical method of centrifugation or sedimentation stratification is used to separate the oil layer and the acid water during the production process. The traditional method of washing and removing acid is eliminated, and the process is shortened. The production cycle of the product reduces the amount of by-product dilute hydrochloric acid. This preparation process has the advantages of solving the peculiar smell of the product, improving the acid reflux of the product, and relieving the pressure on environmental protection. However, there are still cross-linked substances.
Based on these problems, researchers and technicians proposed to use acidic activated clay instead of concentrated sulfuric acid to carry out the telomerization reaction. The catalyst can be used multiple times, reducing the output of by-products and greatly reducing environmental protection pressure; at the same time, the washing process is cancelled and weakly alkaline substances are used. Directly neutralize to neutral, and then physically separate.
3 Analysis of factors affecting the quality of high-hydrogen silicone oil products
Although the current solvent-free method does not use solvents in the application process, it is beneficial to environmental protection and improves product quality.
However, there are still some problems in the solvent-free process: the hydrolyzate contains cross-linked substances, and the hydrogen content of high-hydrogen silicone oil decreases during storage, which affects its stability. Therefore, whether it is a solvent methodor a solvent-free preparation of high-hydrogen silicone oil products, there are currently problems such as large gel content, serious acid return, and lowhydrogen content.
The effect of the adding speed of the co-hydrolysis mixture on the quality:
At present, it is commonly used to add the mixture to the quantitative water.
Because the mixture reacts fiercely with water, too fast the mixture will cause the reaction temperature to rise
faster, the reaction cannot be controlled, and cause more exchanges. Hydrogen-
containing silicone oil is turbid, which affects the product quality and yield. At the same time, incomplete
hydrolysiswill causeacid reversal problems.
The effect on product viscosity:it is hydrolyzed to produce hexamethyl:disiloxane, which has an end-capping effect. Its addition will cause differences in the viscosity of hydrogen-containing silicone oil products. Therefore, reasonable control of the addition of it on the viscosity of hydrogen-containing silicone oil The size plays a decisive role, but also affects the hydrogen content of high-hydrogen silicone oil.
Temperature and vacuum: After the telomerization of high-hydrogen silicone oil reaches equilibrium, it contains more low-boiling substances. Generally, it is necessary to remove low-boiling substances.However, when removing low-boiling substances, the pressure and temperature of the system are more The content has an impact.
The higher the temperature and the lower the pressure, the more low-boiling substances will be released, and the product quality will be better. Otherwise, the product quality will be affected.
