Polyesters glycols

Close to two-thirds of the propylene oxide produced goes to polypropylene glycol and polyester glycols production destined for use in polyurethanes. The polyol diols are made by the base-catalyzed reaction of propylene glycol... 

A. (2.0) Ratio Polymers. 1. High Acid Number Polyester Glycol Effects Figure 2 shows the polymerization viscosity-time-temperature relations for three (2.0) ratio thermoplastic poly(ester-urethane) elastomers. Numbers 1 and 2 were both made from the same reactant lots (I, II, and IX - Table I) at about the same reaction temperatures. 

Data for Natural Polymers 4 5 from Low Acid Number Polyester Glycol... 

B. (3.0) Ratio Polymers Effect of Urethane Group Concentration. Figure 5 shows the polymerization viscosity-time-temperature relations for a (3.0 ratio) thermoplastic poly(ester-urethane) elastomer, Polymer 9. This polymer was made from reactants VI, IV, and X (Table I) the polyester glycol component being intermediate acid number PTAd (0.30). 

The rapid polymerization rate was likely related to the polymer composition wherein the high urethane concentration not only increased polymer melt viscosity but also autocatalyzed further urethane formation.19 However, the intermediate acidity of the polyester glycol is also believed to contribute to the increased polymerization rate due to what may be the particularly favorable balance of its catalytic but reluctant terminal carboxyl groups (at intermediate level) and its reactive terminal hydroxyl groups (in preponderance). 

Again there is no evidence for polymer viscosity loss by reversion in the catalyzed polymerization even on extended reaction at 200°C. Note that the uncatalyzed polymer was still growing at the end of its term in the reactor in keeping with the behavior of Polymers 6 and 7 (Figure 4) which were also made from low acid number polyester glycol, PTAd. 

Comparison of Polymers 14 and 15 in Figure 9 shows fairly similar polymerizations up to the point of shortstop addition. The control, Polymer 5, was slower but alive and growing at 18 minutes of polymerization time, reaching a final torque value of 660 meter-grams. Its steady intermediate polymerizarion rate is seen to be characteristic of uncatalyzed thermoplastic polyurethane elastomer polymerizations based on low acid number PTAd while Polymers 14 and 15 formed faster than usual from such a low acid number polyester glycol component. 

A special polyester glycol type, polycapro-lactone glycol (XXVI), has become well established as a polyurethane adhesive component. And still another macroglycol type, poly butadiene glycol (Poly BD glycol) (XXVII) has gained use in polyurethane adhesive systems. 

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