| 摘要 |
This invention provides a melt transurethane process for the preparation of polyurethanes under solvent free melt conditions. In the transurethane process, a di-urethane monomer is reacted with diol under the melt condition in presence of catalyst like Ti (OBu)4. The high molecular weight of the polymers are achieved by the continuous removal of low boiling alcohol like methanol from the polymerization medium under nitrogen purge and subsequently applying high vacuum. The transurethane process is demonstrated successfully for various diols units such as oligoethylene glycols, simple alkyldiols, cycloaliphatic diols and polyols. The polyurethanes are found to be soluble and thermally stable up to 300 {C for various high temperature applications. The thermal properties such as glass transition temperature in the polyurethanes can be easily fine-tuned by using various di-urethane and diols in the transurethane process. The present invention describes an isocyanate free polymerization route for polyurethanes under melt conditions and the transurethane process is non-hazardous and environmental friendly. The present approach is very efficient for producing high molecular weight polyurethanes and also has potential for large scale preparation. |
