Manufacture of highly polymeric polymethylene terephthalates
Viscosity-stabilized polymethylene terephthalates are made by polycondensing a bis-(hydroxyalkyl) terephthalate in the presence of o-benzoyl benzoic acid. In examples, polyethylene terephthalate was made by effecting ester-interchange between dimethyl terephthalate and ethylene glycol in the presenc...
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| Zusammenfassung: | Viscosity-stabilized polymethylene terephthalates are made by polycondensing a bis-(hydroxyalkyl) terephthalate in the presence of o-benzoyl benzoic acid. In examples, polyethylene terephthalate was made by effecting ester-interchange between dimethyl terephthalate and ethylene glycol in the presence of calcium acetate and antimony oxide to form bis-(beta-hydroxyethyl) terephthalate, then adding phosphorous acid (to render the calcium acetate inactive), next adding o-benzoyl benzoic acid and finally effecting polycondensation at 280 DEG C. and under reduced pressure. Specification 578,079 is referred to. |
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