Fiber-forming polyesters of ketodiols

Fiber-forming melt-spinnable polyester that is optically anisotropic in the melt and consists essentially of, respectively:

• A. substantially equimolar amounts of the recurring units ##STR12## wherein R.sup.1 is m-phenylene or p-phenylene R.sup.2 is ##STR13## each of R.sup.3, R.sup.4, R.sup.6 and R.sup.7 is independently selected from H, CH.sub.3 and Cl;
• R.sup.5 is m-phenylene, p-phenylene, ethylenedioxybis-p-phenylene or p,p'-biphenylene;
• and
• n is 0 or 1;
• provided, however:
• (aa) when n is 0, R.sup.2 is ##STR14## R.sup.3 and R.sup.4 or R.sup.6 and R.sup.7 are both Cl and R.sup.5 is p-phenylene or ethylenedioxybis-p-phenylene, or R.sup.2 is ##STR15## R.sup.3, R.sup.4, R.sup.6 and R.sup.7 and H and R.sup.5 is ethylenedioxybis-p-phenylene;
• and
• (bb) when n is 1, R.sup.1 is m-phenylene, R.sup.2 is ##STR16## R.sup.5 is ethylenedioxybis-p-phenylene or p,p'-biphenylene, one of R.sup.3 and R.sup.4 is CH.sub.3 or Cl and the other is H, and one of R.sup.6 and R.sup.7 is CH.sub.3 or Cl and the other is H;
• and
• B. the recurring units ##STR17## wherein each of X.sup.1 and Y.sup.1 is independently selected from m-phenylene and p-phenylene;
• ##STR18## each of X.sup.3, X.sup.4, X.sup.6, X.sup.7, Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 is independently selected from H, CH.sub.3 and Cl;
• R.sup.5 is m-phenylene, p-phenylene, ethylenedioxybis-p-phenylene or p,p'-biphenylene;
• and
• n is 0 or 1, each of the recurring units (i) and (ii) comprising 40 to 60 mol % of their combined amounts which is substantially equimolar with the amount of (b), provided, however:
• (aa) when n is 0 and one of X.sup.2 and Y.sup.2 is attached at the p-phenylene positions and the other is attached at the m-phenylene positions, then X.sup.3, X.sub.4, X.sup.6, X.sup.7, Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are H and R.sup.5 is p-phenylene or ethylenedioxybis-p-phenylene;
• (bb) when n is 0 and X.sup.2 and Y.sup.2 are both attached at the p-phenylene positions, 1 or 2 of X.sup.3, X.sup.4, X.sup.6 and X.sup.7 and 1 or 2 of Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are independently selected from CH.sub.3 and Cl, the remaining 2 or 3 of X.sup.3, X.sup.4, X.sup.6 and X.sup.7 and the remaining 2 or 3 of Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are H, and R.sup.5 is m-phenylene, p-phenylene or ethylenedioxybis-p-phenylene;
• (cc) when n is 0, X.sup.2 and Y.sup.2 are both attached at the p-phenylene positions, and either X.sup.3, X.sup.4, X.sup.6 and X.sup.7 are each independently selected from CH.sub.3 and Cl and Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are H or X.sup.3, X.sup.4, X.sup.6 and X.sup.7 are H and Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are each independently selected from CH.sub.3 and Cl, then R.sup.5 is m-phenylene.
• (dd) when n is 0 and X.sup.2 and Y.sup.2 are both attached at the m-phenylene positions, 1 or 2 of X.sup.3, X.sup.4, X.sup.6, X.sup.7, Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are independently selected from CH.sub.3 and Cl, the remaining 6 or 7 of X.sup.3, X.sup.4, X.sup.6, X.sup.7, Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are H, and R.sup.5 is is p-phenylene or ethylenedioxybis-p-phenylene;
• (ee) when n is 1, X.sup.2 is ##STR19## and Y.sup.2 is ##STR20## (ff) when n is 1 and X.sup.1 and Y.sup.1 are both m-phenylene, 6 of X.sup.3, X.sup.4, X.sup.6, X.sup.7, Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are independently selected from CH.sub.3 and Cl, the remaining 2 of X.sup.3, X.sup.4, X.sup.6, X.sup.7, Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 are H, and R.sup.5 is p,p'-biphenylene;
• and
• (gg) when n is 1 and one of X.sup.1 and Y.sup.1 is m-phenylene and the other is p-phenylene, each of X.sup.3, X.sup.4, X.sup.6, X.sup.7, Y.sup.3, Y.sup.4, Y.sup.6 and Y.sup.7 is independently selected from CH.sub.3 and Cl, or one of each pair of X.sup.3 and X.sup.4, X.sup.6 and X.sup.7, Y.sup.3 and Y.sup.4 and Y.sup.6 and Y.sup.7 is independently selected from CH.sub.3 and Cl and the other of each pair is H, and R.sup.5 is p,p'-biphenylene.