Example 4
Into a 500 mL four-neck separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, 250 g of an allyl group-terminated polypropylene glycol corresponding to a molecular weight of 7,190 (0.063 mol in terms of functional group of terminal allyl group) and 1.0 g of a platinum catalyst (a solution of a vinylsiloxane complex of chloroplatinic acid, platinum concentration: 1% by weight) were put, and the temperature was raised to 90° C. while the resulting mixture was heated and stirred.
Subsequently, under stirring, 19 g of 1-hydroxy-octamethyltetrasiloxane (the functional group amount of terminal Si—H: 0.066 mol) was added dropwise thereto. At this time, heat was generated, the reaction temperature became 90 to 95° C., and this reaction system was held for six hours. After completion of the reaction, a small excess of 1-hydroxy-octamethyltetrasiloxane was removed under reduced pressure. The temperature was lowered to room temperature. Thereafter, filtration was performed to obtain 255 g of a silanol-group-terminated polypropylene glycol (polymer D) (viscosity: 9.2 Pa·s, molecular weight: 7,800, yield: 95%).
