Cleaning of Apparatus Used in the Manufacture of Polyethylene Terephthalate

摘要

1,187,480. Cleaning metals. EASTMAN KODAK CO. July 27, 1967 [July 18, 1966], No.34653/67. Heading C7E. Apparatus, e.g. pipes or filters, used in the manufacture of polyethylene terephthalate is cleaned by either (A) contacting with a gas at 275 to 350‹C., then with a gas at 325 to 525‹C. and at the same time heating the apparatus to temperatures not greater than 325 and 525‹C. respectively or (B) contacting with glycol at at least 80‹C., and then following either (A) or (B) by (i) heating to 205 to 370‹C. in an oxygen containing atmosphere, and (ii) contacting with an aqueous alkali, pH at least 10, at at least 90‹C.