| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively obtain a thermoplastic polyurethane excellent in softening characteristics and melting characteristics by reacting a diisocyanate with a mixture containing a compound having Zerevitinov active hydrogen atoms and a chain extender under specified conditions in a tubular reactor. SOLUTION: A diisocyanate and a mixture containing a compound having 1-85 eq %, based on the isocyanate, compound having 1.8-2.2 Zerevitinov active hydrogen atoms on the average per molecule and having a number-average molecular weight of 450-5,000 g/mol and 15-99 eq %, based on the isocyanate, chain extender having 1.8-2.2 Zerevitinov active hydrogen atoms on the average per molecule and having a molecular weight of 60-400 g/mol in an NCO/OH ratio of (0.9-1.1)/1 are fed into a tubular reactor provided with an agitator forcibly controlled and freed from any transporting capacity. The reaction mixture is then reacted to completion while it is agitated under conditions in which the ratio of the peripheral speed of the agitator in terms of m/sec to the throughput in terms of g/sec is 0.03 m/g or higher.
|
