| 摘要 |
PURPOSE:To obtain a urethane prepolymer compatible with plasticizers and enabling a coating to be prevented from erosion, by reacting an excess of a polyisocyanate with a polybutadiene polyether polyol. CONSTITUTION:The title product is a urethane prepolymer obtained by reacting an excess of a polyisocyanate with a polybutadiene polyether polyol. The polybutadiene polyether polyol used pref. is a diol. The excess of the polyisocyanate can be achieved by selecting the ratio of the functional groups (NCO and OH) in the two ingredients so that 1.3<=NCO/OH<=10. The reaction is carried out in the presence of a catalyst and a solvent at 70-100 deg.C for several hr. The amt. of the remaining active NCO in the urethane prepolymer should be adjusted to 1.0-10.0%, pref. 2.0-5.0%.
|
