POLYALKYLENE NAPHTHALATE, COMPOSITION THEREOF, FILM, AND PROCESSES FOR PRODUCING THESE

摘要

A polyalkylene naphthalate for a film, which comprises a naphthalenedicarboxylic acid component as a main dicarboxylic acid component and an aliphatic glycol component as a main glycol component, and contains (a) an antimony compound and (b) a quaternary phosphonium sulfonate compound unit having an ester-forming functional group in such amounts that satisfy the following expressions (1) and (2): $wherein\; Sb\; and\; S\; are\; the\; molar\; ratios\; (mmol\%)\; of\; the\; antimony\; compound\; and\; the\; quaternary\; phosphonium\; sulfonate\; compound\; unit\; having\; an\; ester-forming\; functional\; group\; to\; the\; total\; of\; all\; the\; dicarboxylic\; acid\; components\; forming\; the\; polyalkylene\; naphthalate,\; respectively.\; The\; film\; of\; the\; present\; invention\; has\; excellent\; surface\; flatness\; and\; is\; suitable\; for\; use\; as\; a\; base\; film\; for\; a\; magnetic\; recording\; medium.\; It\; is\; also\; excellent\; in\; high-speed\; winding\; properties\; and\; can\; be\; formed\; into\; a\; film\; stably\; and\; produced\; industrially\; advantageously.$