Progressive heating in polyester condensations

Abstract

Abstract UNUSUALLY HIGH REACTION TEMPERATURES MAY BE EMPLOYED IN THE SOLID STATE POLYCONDENSATION OF CRYSTALLINE LINEAR POLYESTER PREPOLYMERS OR RESINS (E.G., POLYETHYLENE TEREPHTHALATE) HAVING A REDUCED SPECIFIC VISCOSITY OF 0.2 OR MORE BY MAINTAINING THE POLYCONDENSATION TEMPERATURE INITIALLY (E.G., AT 200-230*C.) BETWEEN THE STICKING TEMPERATURE OF THE RESIN IN HE AMORPHOUS STATE AND IN THE INITIAL CRYSTALLINE STATE UNTIL THE RESIN STICKING TEMPERATURE HAS SUBSTANTIALLY FURTHER INCREASED AS THE REACTION PROGRESSES, AND THEREAFTER ELEVATING THE POLYCONDENSATION TEMPERATURE EITHER STEPWISE OR GRADUALLY TO A LEVEL (E.G., 240*C. OR MORE) SUBSTANTIALLY ABOVE THE INITIAL CRYSTALLINE STICKING TEMPERATURE IN PRODUCING RESINS OF HIGHER MOLECULAR WEIGHT WITHOUT SIGNIFICANT AGGLOMERATION, THE REACTION RATES ARE GENERALLY FASTER AND HIGHER MOLECULAR WEIGHTS ARE OBTAINABLE THAN HERETOFORE.

Inventors

• 👤 E Maxion

Bibliographic Details