| 摘要 |
A process for the preparation of polyetherurethane foams is disclosed, wherein polyether alcohol and polyisocyanate are foamed in the presence of water or low-boiling propellant and polyalkyleneglycol-polysiloxane mixed block polymer foam stabilizer. In accordance with the invention, the mixed block polymer foam stabilizer has the general formula <IMAGE> wherein M IS UNIFORM OR APPROXIMATELY UNIFORM WITHIN EACH SILOXANE BLOCK OF EACH MOLECULE AND STANDS FOR 5 OR 6; N>/=2; R1 is saturated alkyl of 1 - 8 carbon atoms; R2 is preferably saturated alkyl of 1 - 8 carbon atoms, or the group POA or R31Si-, such as (CH3)3Si; M is a divalent group which in known manner links the adjacent silicon atom to POA; POA corresponds to the formula (CrH2rO)sR3, is composed of polyoxyethylene and polyoxypropylene units in the weight ratio of from 50:50 to 30:70; r being an integer whose range is a corollary function of the specific value of said weight ratio, s being an integer whose specific value or range is a corollary function of the POA block mole weight, and R3 being alkyl of 1 - 8 carbon atoms or phenyl; and POA has a block mole weight of from 1400 - 3000, preferably from 1600 - 2200.
|
