Water-soluble polycoesters, process for their preparation, and their use

A polycoester having a flow point between 220.degree. and 280.degree. C. of the general formula I

• E--CO--R--CO----O--R.sup.1 --O--CO--R--CO).sub.n E.sup.1 (I)
• in which
• R is on average 60 to 85 mol % 1,3-phenylene radicals, 5 to 20 mol % tetramethylene radicals and 10 to 20 mol % radicals of the formula IIa and/or IIb ##STR4## R.sup.1 is on average 60 to 95 mol % ethylene radicals (--CH.sub.2 CH.sub.2 --), 0 to 28 mol % 2,2-dimethyl-1,3-propylene radicals and 5 to 12 mol % polyoxyethylene radicals having an average molecular weight up to 600 and
• R.sup.2 =SO.sub.3 M or --OCH.sub.2 CH.sub.2 CH.sub.2 SO.sub.3 M,
• E, E.sup.1 =--OM, alkoxy having 1 to 4 C atoms or the radical --O--R.sup.1 --OH,
• M denotes a proton, an alkali metal cation or an ammonium ion and
• n is a sufficiently large number that the polycoester has an average molecular weight between 15,000 and 40,000.