PREPARATION METHOD OF POLYDIMETHYLSILOXANE HAVING LOW VISCOSITY, WHICH MINIMIZES THE AMOUNT OF DIMETHYLSILICONE LOSS

摘要

PURPOSE: A preparation method of polydimethylsiloxane having a low viscosity is provided to improve the efficiency of a cracking process by minimizing the amount of dimethylsilicone loss. CONSTITUTION: The preparation method of polydimethylsiloxane having a low viscosity comprises: a step of cracking a hydrolyzed siloxane containing methyl silicate(CH3SiO3) in the presence of an alkali catalyst to form a cyclic polydimethylsiloxane, distilling the cyclic polydimethylsiloxane to obtain residues in liquid phase, adding thereto 1-3pts.wt of an organic solvent with stirring to dissolve the residues; a step of adding thereto 1-2pts.wt of water, based on the amount of the organic solvent which contains the dissolved residues, to extract and remove the alkali catalyst and alkali salts of the methyl silicate; and a step of repeating the extraction process until the pH value of water becomes 7 and distilling the organic solvent to recover a siloxane in the form of dimethylsilicone((CH3)2SiO).