| 摘要 |
1288389 Modified poly(glycolterephthalates) MINNESOTA MINING & MFG CO 27 Aug 1969 [28 Aug 1968 9 June 1969] 42635/69 Heading C3R Clear and virtually colourless poly(glycolterephthalates) are produced from terephthalic acid or dimethyl terephthalate and excess glycol of formula HO-(CH 2 ) n -OH where n = 2-10 in the presence of 0À05 to 1À0 wt. per cent (based on acid or ester used) of a polyfunctional compound having at least 3 functional groups, these being carboxyl, hydroxy or lower alkyl ester groups by polycondensation using 0À005 to 0À05 wt. per cent (based on acid or ester used) of a zinc salt which is soluble in the reaction mixture as the sole catalyst. Up to one half by weight of the terephthalic acid or dimethyl terephthalate may be replaced by isophthalic acid, sebacic acid, 2,6-naphthalic acid or their dimethyl esters and the glycol may optionally be replaced by cyclohexane-dimethanol-1,4. Specific polyfunctional agents named are trimethylolpropane, pentaerythritol, trimethyl trimesate, tetramethyl pyromellitate, dimethylolpropionic acid and trimethyl earballylate. |
