| 摘要 |
<p>The formation of manganese-derivative scale in equipment involved in polyester manufacture is reduced by introduction of a sterically hindered benzoic acid in approximately stoichiometric amount. The acids include 2,6-dichloro-, 2,6-dimethyl- and 2,4,6-trimethylbenzoic acids. The scale is believed to be insoluble manganese terephthalate, presumably formed by reaction of manganese acetate catalyst generated as a result of dimethyl terephthalate with excess ethylene glycol. Preferably an alkali metal salt of an organic acid, such as sodium acetate or lithium acetate is also used to give a synergistic effect in combination with the hindered acid.</p> |
