| 摘要 |
PURPOSE: A method for preparing a silicone gum continuously by using a pyrolysis catalyst is provided, to reduce reaction time and the use amount of a catalyst, to lower reaction temperature and to remove the difficulty of neutralization by using no alkali or acid catalyst. CONSTITUTION: The method comprises the steps of removing moisture from a cyclic monomer represented by £(R¬1)2SiO|m with injecting N2 gas in vacuum at 60-65 deg.C; adding the cyclic monomer, a pyrolysis catalyst represented by R¬2_4-X-O£SiO|-X-R¬2_4 and a chain stopper to a reactor and premixing them at 20-40 deg.C; increasing the temperature to 85-95 deg.C, maintaining the temperature for 30-60 min, increasing the temperature to 115-120 deg.C and maintaining the temperature for 30-60 min to carry out ring opening polymerization for obtaining a high viscosity silicone gum; decomposing a catalyst at 170-175 deg.C; removing a cyclic monomer and the unreacted materials in vacuum of 1-10 torr; discharging the gum by the pressure of N2 with reducing the temperature to 60-80 deg.C; and collecting the cyclic monomer removed in vacuum and the cyclic monomer discharged in the moisture removing process for reusing it, wherein R¬1 is an alkyl group of C1-C8, a cycloalkyl group, an alkenyl group or an allyl group; m is an integer of 3-20; R¬2 is an alkyl group of C1-C8, a cycloalkyl group, a vinyl group or a phenyl group; and X is N, B or P.
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