Melt transurethane process for the preparation of polyurethanes
First Claim
1. A solvent free, non isocyanate, melt transurethane process for the preparation of polyurethane or its co-polymer having formula 1, which comprise condensing di-urethane monomer with diol, in the presence of a catalyst, at a temperature in the range of 50-300°
- C. to obtain the resultant melt, removing oxygen completely from the above said melt by purging it with nitrogen, under vacuum pressure of 1-0.001 mm Hg for its subsequent evacuation, under stirring, cooling and continuing the above said polymerization reaction for a period of 4-24 hrs, followed by the removal low boiling alcohols from the above said melt condensation to obtain the desired polymer, blending the resultant trans poly urethane with thermoplastics or thermosets either in solution or melt, in a molar or weight ratio of 1 to 99% to obtained the desired polymer blend.
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Abstract
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.
6 Citations
22 Claims
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1. A solvent free, non isocyanate, melt transurethane process for the preparation of polyurethane or its co-polymer having formula 1,
which comprise condensing di-urethane monomer with diol, in the presence of a catalyst, at a temperature in the range of 50-300° - C. to obtain the resultant melt, removing oxygen completely from the above said melt by purging it with nitrogen, under vacuum pressure of 1-0.001 mm Hg for its subsequent evacuation, under stirring, cooling and continuing the above said polymerization reaction for a period of 4-24 hrs, followed by the removal low boiling alcohols from the above said melt condensation to obtain the desired polymer, blending the resultant trans poly urethane with thermoplastics or thermosets either in solution or melt, in a molar or weight ratio of 1 to 99% to obtained the desired polymer blend.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
Specification