Aromatic polymers containing ketone linking groups and process for their preparation

Claim 1

A process for the preparation of aromatic polymers having reduced viscosity of between 0.8 and 3.0, as measured at 25° C on a solution of polymer in concentrated sulphuric acid of density 1.84 g/cm 3 containing 1 g of polymer in 100 cm 3 of solution, which comprises heating at a temperature of 250° to 400° C a monomer mixture comprising 1. 49 to 50% molar of a di(alkali metal) salt of at least one bisphenol of the formula ##STR21## at least 95% of the phenolic OH groups being in the para position, and 2. 51 to 50% molar at least one dihalo compound of the formula ##STR22## where Q is SO 2 or CO, X is F, Cl or Br, n is a positive integer not exceeding 3 and m is 0 or 1, and the molar percentages of said di(alkali metal) salt and said at least one dihalo compound sum to 100%, said di(alkali metal) salt being present as a suspension in a diaryl sulphone having the formula ##STR23## in which Y is a direct link, an oxygen atom or two hydrogen atoms (one attached to each benzene ring) and Z and Z' are selected from hydrogen atoms and phenyl groups and may be the same or different, the proportion of SO 2 to CO groups in the monomer mixture being not greater than 25%.