Silicone oil usually refers to polysiloxane products that remain liquid at room temperature.Silicone oil and its derivatives make up about 40% of silicone products.Hydrogen containing silicone oil is one of the most important varieties.Its molecular formula is me3sio (me2sio) sime3.According to the different values of m and n, it can be divided into total hydrogen containing silicone oil (m_0, n=0) and partial hydrogen containing silicone oil (m_O, 0).Due to the introduction of silicone groups in the main chain, the film can be cross-linked at low temperature and a waterproof layer can be formed on the surface of the material.It is widely used in building materials, metal, leather and other industries, as well as anti-yellowing agent of silicone rubber.At the same time, silicone can be added with compounds containing unsaturated bonds, and different groups are introduced in hydrogen-containing silicone oil to get different products, which are mainly used as silicone surfactant, coating homogenizer and polyurethane foam homogenizer.Pesticides etc.

    1 Preparation of silicone oil containing all hydrogen

    1.1 Cohydrolytic shrinkage method

    The traditional method is to add a quantitative mixture of methylodichlorosilane and trimethylosilane to the reactor with solvent and water.After hydrolysis, the acid water is separated and concentrated sulfuric acid is added to the reactor.After the reaction, the product was stratified, washed with superwater to neutral, removed low boiling matter, filtered, and decolorized.Solvents are generally hydrocarbons or benzene derivatives, and most of the solvents used at present are heptane and toluene.

    1.2 Siloxane catalytic equilibrium method

    The principle of this method is similar to the cohydrolytic shrinkage method, but the ending agent is hexamethyldisiloxane (mm).Firstly, methyl hydrodichlorosilane and MM were added to the reactor to form a mixture, and then concentrated sulfuric acid was added for a period of time. Water was slowly added to the catalytic equilibrium reaction, and then the upper product was washed to neutral and distilled under pressure.The target product is filtered.

    Little has been written about the law.Methyl hydrodichlorosilane was dissolved in an organic solvent, absolute ethanol was added to the alcohololysis solution for 1 hour, and then 2 times the solvent and 4 times the water were added to the alcohololysis product for hydrolysis.At the end of the reaction, the acid water was separated statically, the upper layer of the product was washed to neutral, and the hydrolysate was distilled by vacuum distillation.The hydrolysate was then mixed with MM and catalyst for equilibrium reaction to separate sulfuric acid.The product was washed to neutral, dried and filtered to obtain the target product. 

    2 Part preparation of hydrogen containing silicone oil

    2.1 Polymerization of silicone oil containing all hydrogen

    The polymerization reaction was carried out with total hydrogen silicone oil, dimethylcyclosiloxane (DMC) and MM as raw materials under the action of catalyst.The catalysts used in this method are generally divided into two categories: concentrated sulfuric acid, trifluoromethyl sulfonic acid and other liquid catalysts;Acid clay, acid zeolite, acid cation exchange resin and other solid catalysts.

    2.2 Co-hydrolysis and shrinkage of mixed organochlorosilanes

    The method of the invention is to mix a mixed solution of methyl hydrodichlorosilane, dimethyl dichlorosilane and trimethyl chlorosilane with a solvent in a reactor, and then add water by drop.After the reaction is complete, the acidic water is separated, and concentrated sulfuric acid is added during the polymerization process to separate the sulfuric acid.The top solution is washed to neutral, removed and filtered into the finished product.

    The main current method of producing hydrogen containing silicone oil is hydrolyzing organochlorosilanes.How to control the hydrolysis rate is the key link of product quality.Therefore, the main improvement direction of the quality of hydrogen containing silicone oil per mu in the future is to use new technology to control the hydrolysis rate, pay attention to the purity of hydrogen containing monomer, so as to avoid the cross-linking of flocculent substances that affect the quality of the product.The current catalyst is mainly concentrated sulfuric acid, low price, but serious corrosion to the container, not conducive to environmental protection.Solid catalysts have high industrial application value and high price. The development of new low-cost and high-efficiency catalysts is also an important research direction.