Row inter-tube falling film melt phase polycondensation reaction method and reactor thereof

Abstract

The invention relates to a row inter-tube falling film melt phase polycondensation reaction method. A melt prepolymer flows downwards from a film distribution plate and holes between tubes, a waterfall falling film flowing is formed between the U-shaped tubes in rows so that a melt phase polycondensation can be performed, and a melt slides down from the tubes, then condensed at the bottom of a reactor and discharged after stirring is performed to be homogenized through a stirrer. The reactor implementing the method is of an overall vertical structure and comprises a shell, a heating medium box at the upper end, a material box connected with the heating medium box, the U-shaped tubes, a bottom shell at the lower end, a stirrer and the like. The U-shaped tubes are perpendicularly suspended and arranged in rows, uniformly penetrate through holes in the film distribution plate, and the ends of the U-shaped tubes and the heating medium box are communicated to allow a heating medium to flow. The reactor has the advantages that the flowing resistance is small, no dead zone is generated, the film forming area is large, the surface updating speed is high, the standing time is uniform and controllable, and flexible production is met. The method is applicable to production of polyethylene glycol terephthalate and other polymers.

Description

technical field [0001] The invention relates to a falling film type melt polycondensation reaction method and melt polycondensation reaction equipment in polymer production. Background technique [0002] Polycondensation reaction is a reversible polymerization reaction that continuously produces small molecular compounds, including polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate ( Polymers such as PBT), polyethylene naphthalate (PEN), polyamide (PA) and polycarbonate (PC) are all prepared by polycondensation. The similar feature of this kind of polymer is that in the process of polycondensation reaction, the devolatilization process of eliminating small molecular compounds must be continuously carried out to promote the continuous positive reaction, so the viscosity of the material is extremely high, especially in the late stage of polycondensation, the material The dynamic viscosity will change by an order of magnitude. Th...

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Problems solved by technology

Especially when preparing high-viscosity materials, the falling film reactor outside the tube can make the material flow outside the tube by gravity alone, providing a suitable residence time so that the material can fully react, but the complete wall-attached falling film flow will Due to the speed difference between the inner and outer layers of the melt film, the flow rate of the outer layer of the liquid film is fast, while the inner layer of the film is slower, causing some materials to be attached to the internal components of the reactor for a long time and degrade and turn yellow, affecting the quality of the final product. However, the free falling film of the falling strip will make the flow rate of the melt film free fall too fast and the residence time too short, and the film surface shrinks significantly during the process of the melt film falling, and the film forming efficiency is very low.

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