| 摘要 |
Siloxane-oxyalkylene block copolymers are prepared by heating (1) an organosilicon polymer containing at least one acyloxy radical attached to a silicon atom having a silicon functionality of 2 to 4 (2) a polyoxyalkylene hydroxyl polymer having at least 2 oxyalkylene groups, and removing a carboxylic acid corresponding to the acyl groups of the siloxane polymer from the mixture. The reaction is preferably performed at 75-200 DEG C. with a current of inert gas passing through the reaction mixture. The products which contain at least one polysiloxane block and at least one polyoxyalkylene block are useful as emulsifying agents for hydrocarbon water systems and as stabilizing agents for polyurethane foams. In an example (XV) siloxane-oxyalkylene block copolymers of the invention are used to stabilize polyurethane foams prepared from toluene di-isocyanate, polypropylene glycol, glycerol started polypropylene triol, water, triethylamine and dibutyltin dilaurate. |
