Patent DE-10041595-A1 (DE)
Title: Apparatus for continuous production of polybutylene terephthalate comprises a series of three or four reactors, of which the first and/or second has no externally driven stirrer
Inventor: NAKAMOTO HIDEKAZU
IPC: C08G63/183
Filed: 2000-08-24
Abstract: Apparatus for continuous production of polybutylene terephthalate (PBT) comprises a series of three or four reactors, of which the first and/or second has no externally driven stirrer.  Apparatus for continuous production of PBT comprises: a first reactor (3) for reacting an aromatic dicarboxylic acid (mainly terephthalic acid or its derivatives) with a diol (mainly 1,4-butanediol) to form an oligomer with an average degree of polymerization (DP) of 2.2-5; a second reactor (14) for polycondensation of the oligomer to form a polymer with a DP of 25-40; a third reactor (18) for further polycondensation of the polymer to form a polyester with a DP of 70-130; and optionally a fourth reactor (23) for further polycondensation of the polyester to form a polyester with a DP of 150-200; where the first and/or second reactor has no externally driven stirrer. Independent claims are also included for the following: (1) a process for continuous production of PBT, comprising: reaction of an aromatic dicarboxylic acid (mainly terephthalic acid or its derivatives) with a diol (mainly 1,4-butanediol) in a first reactor (3) to form an oligomer with a DP of 2.2-5; polycondensation of the oligomer in a second reactor (14) to form a polymer with a DP of 25-40; and further polycondensation of the polymer in a third reactor (18) to form a polyester with a DP of 70-130; where the third reactor comprises a horizontal cylindrical reaction vessel with a feed inlet in the bottom part at one end, a product outlet in the bottom part at the other end, a volatiles outlet in the upper part, and a longitudinal stirrer whose axle rotates near the inside wall of the vessel and, depending on the viscosity of the reaction mixture, is provided with several groups of shankless stirrer blades; (2) a process for continuous production of PBT, comprising: reaction of an aromatic dicarboxylic acid (mainly terephthalic acid or its derivatives) with a diol (mainly 1,4-butanediol) in a first reactor (3) to form an oligomer with a DP of 2.2-5; polycondensation of the oligomer in a second reactor (14) to form a polymer with a DP of 25-40; further polycondensation of the polymer in a third reactor (18) to form a polyester with a DP of 70-130; and further polycondensation of the polyester in a fourth reactor (23) to form a polyester with a DP of 150-200; where the fourth reactor comprises a horizontal cylindrical reaction vessel with a feed inlet in the bottom part at one end, a product outlet in the bottom part at the other end, a volatiles outlet in the upper part, and a pair of longitudinal axles that rotate near the inside wall of the vessel and are equipped with stirring paddles; (3) a process for continuous production of PBT, comprising: reaction of an aromatic dicarboxylic acid (mainly terephthalic acid or its derivatives) with a diol (mainly 1,4-butanediol) in a first reactor (3) to form an oligomer with a DP of 2.2-5; polycondensation of the oligomer in a second reactor (14) to form a polymer with a DP of 25-40; and further polycondensation of the polymer in a third reactor (18) to form a polyester with a DP of 70-130; where the molar ratio of aromatic dicarboxylic acid to diol in the first reactor is 1:1.7-3.0.