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AssigneeTeijin Limited
InventorsShoji Kawase, Takatoshi Kuratsuji, Hiroo Inata, Kazuyoshi Suzuki, Takeo Shima
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A process for preparing polyesters, which comprises reacting (A) a difunctional carboxylic acid component containing at least 50 mol% of a naphthalene dicarboxylic acid and/or its ester-forming derivative, (B) a diol component containing an aromatic group and at least 50 mol% of a 4,4'-bis-(.omega.-hydroxyalkoxy)diphenylsulfone and (C) an aliphatic or alicyclic diol component, the molar ratio of component (B) to component (A) being 0.05-1, and the molar ratio of the sum of components (B) and (C) to component (A) being 1.1-3.0; and then polymerizing the resulting reaction product in the presence of a catalyst while distilling off the excess of the component (C) out of the reaction system, thereby to form a polymer having a reduced viscosity of at least 0.5.
Polyesters having a reduced viscosity, as measured on an o-chlorophenol solution in a concentration of 1.2 g/dl at 35.degree. C. of at least 0.5 which comprises (A) a difunctional carboxylic acid component containing at least 50 mol% of a naphthalene dicarboxylic acid and/or its lower alkyl ester or aryl ester, (B) a diol component containing an aromatic group and at least 50 mol% of said diol component being a 4,4'-bis-(.omega.-hydroxyalkoxy)diphenylsulfone of the general formula ##STR3## wherein n is an integer of 2 to 6, and (C) is a diol component of the general formula
Dependencies are inferred from the claim text.