Nippon Ester Co., Ltd.

Tetsuo Matsumoto

Takayuki Imamura

Keizo Tsujimoto

Atsuko Ueda

Eiji Ichihashi

Kouzi Shinogi

Bunpei Imura

Koji Shinogi

Katsuto Matsuzawa

Akiko Kuroyanagi

Shunichiro Hamada

Satomi Nagai

A process for producing a polyester film is disclosed, which comprises melt-mixing from 3 to 12 parts by weight of a master polymer comprising a poly(alkylene terephthalate) which contains from 0.3 to 3 wt % inorganic lubricant and has an intrinsic viscosity of 0.5 or higher with from 97 to 88 parts by weight of a poly(alkylene terephthalate) containing no inorganic lubricant and having an intrinsic viscosity of 0.5 or higher, and forming the resulting mixture into a film by the electrostatic casting method. The master polymer is obtained by a process comprising adding to a poly(alkylene terephthalate) oligomer having an average degree of polymerization of 10 or lower an alkylene glycol slurry of an inorganic lubricant and specific amounts of a potassium compound and a phosphorus compound, depolymerizing the oligomer, subsequently adding specific amounts of antimony trioxide and germanium dioxide, and then effecting polycondensation. By this process, a polyester film having an excellent color tone can be produced with a high producibility and a high operation efficiency.

Process for producing polyester film

A flame resistant polyester produced by addition and copolymerization of a phosphorus compound represented by general formula (I) below as a diol component of the polyester in an amount of 500 ppm or more in terms of phosphorus atom content in the polyester, which polyester has alkylene terephthalate units as main repeating units and which has an intrinsic viscosity of not less than 0.5 measured at 20.degree. C. in a mixture of equal weight of phenol and tetrachloroethane: ##STR1## where E is --CH.sub.2 CH.sub.2 --, Ar is an aromatic group or an aromatic group substituted by a lower alkyl group or a halogen atom, and m and n denote, respectively, integers the sum of which is from 1 to 20.

Flame resistant polyester from di aryl-di(hydroxyalkylene oxy)aryl

A polyester, wherein pendent phosphorus atoms are bound to the main chain of the polyester, having an excellent flame resistance and a high intrinsic viscosity can be stably produced without deteriorating the properties of said polyester by preliminarily copolymerizing a polyester with a specific unsaturated compound and then reacting the unsaturated bond thus-formed with a specific phosphorus compound having a P-H bond.

Process for producing flame resistant polyester

A random copolyester is described, comprising recurring moieties represented by formula (I), (II), and (III), and having an intrinsic viscosity of not less than 0.5, wherein said recurring moieties of formulae (I) and (II) are existing substantially in equimolar amount and recurring moieties of formulae (I) and (III) are present in a molar ratio of from 95/5 to 5/95 ##STR1## wherein Ar.sub.1 represents a trivalent aromatic group and Ar.sub.2 represents a divalent aromatic group. In formulae (I), (II), and (III), aromatic rings may be substituted with an alkyl group or an alkoxy group having from 1 to 20 carbon atoms, an aryl group or aryloxy group having from 6 to 20 carbon atoms, or a halogen atom. The copolyester obtained is excellent in heat resistance and flame retardance.

Phosphorus containing copoleyster

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Aichi, Japan

Tetsuo Matsumoto