Nippon Steel Corporation

Nippon Steel Chemical Co., Ltd.

Hiroharu Inoue

Takero Teramoto

Kazuaki Harada

Kazuhiro Sugiyama

Masao Kimura

Koichi Fujishiro

Masanao Kawabe

Ikuro Yamaoka

Shuichi Mitamura

An aromatic polyester carbonate comprising structural units represented by the following formulae (A), (B), (C), and (D) and satisfying the following relationship when the mole fractions of the structural units represented by the formulae (A), (B), (C), and (D) are defined as a, b, c, and d, respectively: ##EQU1## and having an inherent viscosity [.eta..sub.inh ] in a solution at a concentration of 0.5 g/dl in p-chlorophenol as a solvent at 50.degree. C. of 1.0 dl/g or higher, or being insoluble in the solvent, and having liquid crystal properties ##STR1## wherein R is the same or different and represent an alkyl, phenyl group or a halogen, and n represents an integer of 0 to 4; ##STR2## X.sup.1 represents a substituted or non-substituted phenyl group, an alkyl group having 3 to 6 carbon atoms or a halogen;

Aromatic polyester carbonate from diphenol mixture

A soluble polyimide having a chain member substantially represented by the formula:

Soluble copolyimide from 9,9-bis (4-amino phenyl) fluorene

A soluble heat-resistant aromatic polyamide having amide bonds at the terminal ends thereof represented by the formula (I):

Soluble heat-resistant aromatic polyamide terminated with aromatic amido

Disclosed is a process for the preparation of a naphthalene-2,6-dicarboxylic acid dialkali metal salt which comprises heating an alkali metal salt of naphthoic acid and/or a dialkali metal salt of naphthalene-dicarboxylic acid under pressure with carbon dioxide gas in the presence of a catalyst, wherein an aprotic polycyclic aromatic compound having 2 or 3 rings is used as a reaction medium. Naphthalene-2,6-dicarboxylic acid dialkali metal salt can be obtained in high yield and selectivity with a good reproducibility of the reaction.

Process for preparation of naphthalene-2,6-dicarboxylic acid dialkali

A heat-resistant polyamide having a repeating unit represented by the formula (I):

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Kawasaki, Japan

Hiroharu Inoue