A kind of preparation method of simethicone oil

Abstract

The invention provides a preparation method of simethicone oil. The method comprises the steps of: pretreatment of hydroxyl-terminated polydimethylsiloxane; uniformly mixing the pretreated hydroxyl-terminated polydimethylsiloxane and trimethylchlorosilane, stirring and adding at 50-100° C. Pressure reaction for 1‑8h; release the pressure to remove trimethylchlorosilane and hydrogen chloride to obtain simethicone oil. The raw materials of the present invention are easy to obtain, the preparation method is simple, the preparation conditions are mild, and it is easy to realize; there is no addition of external reagents such as catalysts, and no introduction of impurities such as metal ions and non-volatile acids, so that the purity of the target product is high; and the post-treatment is simple. , no generation of waste water and waste salt, green and environmentally friendly; and the reaction is thorough, trimethylsilane is capped, the yield of the target product is high, the hydroxyl content is low, and there is no introduction of other heteroelements.

Description

technical field [0001] The invention relates to a preparation method of high-purity dimethyl silicone oil, which belongs to the technical field of chemical industry. Background technique [0002] Dimethicone oil, also known as methyl silicone oil and polydimethylsiloxane, is a colorless, transparent, viscous liquid, tasteless, odorless, and non-toxic. It has excellent hydrophobicity, moisture resistance, good light transmission, and chemical Stability, widely used in insulation, heat-resistant, moisture-proof fillers, high-efficiency defoamers, release agents, lubricants and surface treatment agents. At present, the preparation methods of simethicone oil are mainly as follows: [0003] 1. Prepare simethicone oil by acid method; generally use dimethylcyclosiloxane and hexamethyldisiloxane as raw materials to prepare through equilibrium reaction. The catalysts used are mainly sulfuric acid and solid acid; the preparation of silicone oil using sulfuric acid as a catalyst requ...

AI Technical Summary

Problems solved by technology

Both steps of this method use acid, which also has the problem of relatively large waste acid production in waste water, which is not environmentally friendly, and post-treatment such as washing with water is relatively complicated, and the overall preparation steps are cumbersome. A certain non-volatile acid is difficult to remove, thereby contaminating the product and reducing the purity; and, after a long period of use, there will be a large amount of invalid solid acid, which is difficult to handle

In addition, there is a dehydroxylation step in the method, and hexamethyldisilazane is added to introduce heteroelement nitrogen into the silicone oil, which makes the obtained silicone oil prone to yellowing. At the same time, the price of the raw material hexamethyldisilazane is relatively high, which is not conducive to cost reduction.

[0007] 3. Alkali method is used to prepare silicone oil, generally using temporary catalyst tetramethylammonium hydroxide or potassium hydroxide; tetramethylammonium hydroxide is used as catalyst to produce trimethylamine during the decomposition process, which has a fishy smell and is not conducive to environmental protection, and Still there is a certain amount of metal ions in tetramethylammonium hydroxide (the traditional method for preparing tetramethylammonium hydroxide has defects such as high content of impurity ions); using potassium hydroxide as a catalyst metal ion content will be higher, reducing the target product the purity of

[0008] For example, the Chinese patent document CN102643427A discloses a method for catalyzing the production of high-purity simethicone oil with anhydrous strong base catalyst, using hexamethyldisiloxane of low molar mass as the head-sealing agent, and using anhydrous tetramethylhydroxide The ammonium methanol concentrated solution is used as a catalyst to catalyze the ring-opening of dimethylcyclosiloxane with low molar mass. The simethicone oil prepared by this invention has high purity, but it also has the above-mentioned problems, that is, tetramethylcyclosiloxane Ammonium hydroxide will decompose to produce trimethylamine in the later stage of the reaction, which has a fishy smell and is not conducive to environmental protection, and there is still a certain amount of metal ions in tetramethylammonium hydroxide, which will pollute the target product and reduce the purity; and the overall preparation steps are cumbersome, and the use of Tetramethylammonium hydroxide methanol solution will inevitably produce a small amount of methoxy-terminated silicone oil

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