It is defined relative to high hydrogen containing silicone oil (hydrogen value is 1.6). It contains silicon hydrogen bond with relatively low activity. It is the basic raw material for the synthesis of modified silicone oil, such as polyether modified silicone oil and alkyl modified silicone oil. It is also the crosslinking agent of addition silicone rubber and can also be used for hydrophobic treatment of materials. At present, the hydrogen content of the most common low hydrogen containing silicone oil on the market is generally 0.1/0.18/0.22/0.36/0.5/0.8 and other specifications. Different low hydrogen containing silicone oils can be used according to different applications.

Safety instructions

Low hydrogen silicone oil products are colorless, viscous and transparent liquid, non corrosive, flammable, insoluble in water and easily soluble in organic solvents. The temperature of storage place should be 20 ℃ ~ 40 ℃. During transportation, they should be transported as non dangerous goods.

synthetic method

There are three main methods for the synthesis of low hydrogen containing silicone oil.

First, halosilane method: the starting materials are methylhydrodichlorosilane, dimethyldichlorosilane, trimethylmonochlorosilane and solvent, which are hydrolyzed and decomposed in the reactor, and then polymerized with concentrated sulfuric acid or solid acid catalyst. After the reaction, the solvent and low boiling matter are removed from the oil layer, and then decolorized and filtered to obtain the finished product; (disadvantages: violent reaction, difficult to control, complex process, large amount of HCl gas will be released during the reaction process, which is not environmental friendly)

The second is ring opening copolymerization method: octamethylcyclotetrasiloxane (D4) and tetramethylcyclotetrasiloxane (dh4) are used for ring opening copolymerization. The reaction is generally carried out in nitrogen atmosphere, and sulfuric acid, p-toluene, sulfonic acid or acidic clay can be used as catalyst; (disadvantages: the reaction process is violent and the raw materials are expensive. At present, it is only limited to laboratory research.)

The third is the high hydrogen containing silicone oil telomerization method: the high hydrogen containing silicone oil terminated by trimethylsilicon is used for telomerization reaction with octamethylcyclotetrasiloxane (D4) and hexamethyldisiloxane (mm) under acid catalytic conditions. The catalyst can be sulfuric acid, trifluoromethylsulfonic acid or solid heteropoly acid.

Conclusion: To sum up, the optimum conditions for synthesis by using this production process are: reaction temperature 26 ℃, reaction time 8h; The amount of high hydrogen silicone oil has little effect on the conversion of monomer, and the end capping agent mm has obvious effect on the conversion of monomer. Other production contents need to be adjusted according to different formulas.