Method for removing and recovering reaction monomer

Abstract

This method for removing the unreacted monomers from the vinylidene chloride resin slurry comprises keeping an aqueous medium in the vinylidene chloride resin slurry containing the unreacted monomers and obtained by polymerization in the aqueous medium in a boiling state at <=80 deg.C temperature under a reduced pressure and vaporizing the unreacted monomers. The method for recovering the unreacted monomers from the vinylidene chloride resin slurry comprises cooling the removed unreacted monomer component, separating water, then further cooling the unreacted monomer component, liquefying the gaseous unreacted monomers and recovering the unreacted monomers.

Description

technical field [0001] The present invention relates to removing unreacted vinylidene chloride-based resins while preventing quality deterioration such as coloring of vinylidene chloride-based resins from a vinylidene chloride-based resin slurry (slurry) containing unreacted monomers obtained by polymerization in an aqueous medium. A method of monomer, and a method of recovering unreacted monomer. Background technique [0002] In the past, as a method of separating and removing residual monomers from vinyl chloride-based resin slurries, it was proposed in JP-A-51-135990 to polymerize vinyl chloride or a monomer mixture mainly composed of vinyl chloride in an aqueous medium. , in the process of transferring the obtained vinyl chloride resin slurry to the separation tank with a pipeline, the slurry is rapidly heated to a temperature of 80-150°C by blowing water vapor into the slurry or performing external heating while blowing water vapor , and the...

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Problems solved by technology

[0003] However, when this method of separating and removing residual monomers from a vinyl chloride-based resin slurry is applied to a vinylidene chloride-based resin slurry containing unreacted vinylidene chloride monomer, since the vinylidene chloride-based resin and Compared with vinyl chloride-based resins, the thermal stability is poor, so there is a disadvantage that keeping at a temperature above 80°C for a long time will bring about poor quality results such as coloring of vinylidene chloride-based resins.

[0004] In addition, when the temperature in the pipeline transportation and the temperature in the separation tank are lowered, when the method of the above-mentioned prior art is applied to the vinylidene chloride-based resin slurry, since the boiling point of the vinylidene chloride monomer is 31.7°C and the temperature of the vinyl chloride monomer The boiling point of -13.8 ℃ is significantly higher than that, and it is extremely difficult to remove unreacted monomers, so it is very difficult to reduce the content of unreacted monomers in the slurry to a low level below about 1500ppm (resin weight conversion)

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