Polymer producing method and apparatus and polymer degassing method and apparatus

Abstract

The objective of this invention is to inhibit yellowing of a polymer caused by thermal decomposition when degassing a monomer from a reactant. This invention provides a polymer degassing apparatus comprising a barrel-shaped horizontal container 41 having a supply port 42 for supplying a reactant, a discharge port 43 for discharging a reactant, a stirring means 45 for stirring a reactant, and a degassing means for drawing a gas via a degassing port 44 of the horizontal container, wherein the supply port is positioned below the molten liquid level of the reactant, a recovery container 37 that is connected to the degassing port for recovering a volatile substance in the gas and a vacuum pump 36 are provided, and the stirring means comprises a plurality of stirring rods 46 oriented along the same direction as the axis in the horizontal container and coupling members 47 for coupling the stirring rods along the same direction as the axis, provided that the coupling members are placed at a distance from the virtual rotation center of the stirring means.

Description

technical field [0001] The invention relates to a polymer manufacturing method, a manufacturing device, a polymer devolatilization device and a devolatilization method, in particular to a technology for removing unreacted monomers from ring-opening polymers such as polylactic acid. Background technique [0002] Polylactic acid, one of polymers synthesized by ring-opening polymerization, is a colorless and transparent polyester produced from lactic acid, which is one of hydroxycarboxylic acids, as a raw material. As one of the methods for synthesizing polylactic acid from lactic acid, there is a known method: condensing lactic acid to form an oligomer, adding a catalyst such as antimony oxide to depolymerize it to produce lactide as a cyclic condensate (dimerization of lactic acid) body), ring-opening polymerization is carried out by adding a catalyst such as tin octoate to the lactide. [0003] As a method for polymerizing polylactic acid, for example, there is known a cont...

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Problems solved by technology

However, for lattice-shaped stirring blades, if the viscosity of the reaction liquid does not reach a certain level, the performance of lifting the reaction liquid for stirring and devolatilization will be significantly reduced

Therefore, it is presumed that the devolatilization performance is deteriorated for the reaction solution with low viscosity at the initial stage of the monomer removal process.

[0020] In addition, in Patent Documents 5 and 6, there is no description of the method and apparatus for the monomer removal step after the ring-opening polymerization step, and the technology of an appropriate monomer removal step is required to synthesize a high-quality polymer.

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