Vinyl Chloride Polymerization Monomer Supply Control
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Solution Overview
Problem
During mass polymerization of vinyl chloride resin, the decreasing average distance between resin particles leads to excessive coagulation or friction, resulting in the generation of abnormal products such as fine-particle, oversize-particle, and lumpy products, which affects the quality and processability of the resin.
Innovation Solution
An apparatus and method for mass polymerization that involves the additional supply of a monomer to the reactor when the monomer-to-polymer conversion ratio is between 30% to 70%, specifically to the lower portion of the reactor, to maintain a stable average distance between particles and prevent excessive coagulation, using a reactor equipped with a supply pipe, condenser, and pressure control valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mass polymerization is carried out without additional monomer supply, then the reaction rate is fast and yield is high, but the average distance between resin particles decreases leading to excessive coagulation and friction
Solution Approach 1:
The patent applies dynamic monomer supply during the polymerization process. The monomer supply rate is adjusted based on the conversion ratio: initial monomer is supplied at a first rate when conversion is 0-30%, then monomer supply rate is increased to a second rate when conversion reaches 30-70%, and finally monomer supply rate is adjusted to a third rate when conversion reaches 70-90%. This dynamic adjustment maintains optimal particle spacing throughout the reaction, preventing excessive coagulation while preserving high reaction rate and yield.
Solution Approach 2:
The patent changes the monomer supply parameter based on the conversion ratio stages. By adjusting the monomer supply rate according to the current conversion level (0-30%, 30-70%, 70-90%), the system maintains appropriate liquid monomer content to prevent particle coagulation. This parameter change strategy resolves the contradiction by allowing high productivity through optimized monomer addition timing and rate.
2Manufacturing precision
If monomer is continuously supplied throughout polymerization, then particle coagulation is prevented, but the reaction system becomes complex and control becomes difficult
Solution Approach 1:
The patent segments the polymerization process into three distinct stages based on conversion ratio: initial stage (0-30%), middle stage (30-70%), and final stage (70-90%). Each stage has its own monomer supply rate characteristic. This segmentation simplifies control by providing clear decision criteria for monomer addition at each phase, avoiding the complexity of continuous adjustment while maintaining effective particle spacing.
Solution Approach 2:
The patent establishes predetermined monomer supply rates for each conversion stage before the actual polymerization proceeds. The control strategy is pre-planned with specific supply rates assigned to each stage (first rate for 0-30%, second rate for 30-70%, third rate for 70-90%). This preliminary action approach simplifies real-time control by referring to pre-established guidelines rather than requiring complex real-time optimization algorithms.
3Temperature
If liquid monomer amount is insufficient, then overheating occurs due to inadequate heat removal, but adding more monomer increases the risk of coagulation
Solution Approach 1:
The patent implements feedback control by monitoring the conversion ratio and adjusting monomer supply rates accordingly. The system detects when conversion reaches specific thresholds (30% and 70%) and automatically adjusts the monomer supply rate to match the changing reaction conditions. This feedback mechanism ensures adequate heat removal capacity at each stage while preventing particle coagulation through appropriate liquid monomer maintenance.
Solution Approach 2:
The patent dynamically adjusts monomer supply rates based on conversion ratio stages to balance heat removal needs with coagulation prevention. In the middle stage (30-70% conversion) where heat accumulation is most problematic, the system increases monomer supply to a second rate to enhance heat removal capacity. This dynamic adjustment prevents overheating while maintaining particle spacing to avoid coagulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses the generation of abnormal products, maintaining a normal particle-size distribution of 75 to 200 μm and enhancing the quality and processability of the vinyl chloride resin by controlling overheating and particle collision.
Implementation Method 1
a vinyl chloride monomer (VCM), an initiator, and, as needed, a reaction additive are supplied and polymerized
Implementation Method 2
a condenser, and a pressure control valve, and further comprises an additional supply pipe for additionally supplying a monomer into the reactor
Data Source
AI summary
Disclosed are an apparatus for mass polymerization of a vinyl chloride resin which may suppress generation of abnormal products (fine-particle products, oversize-particle products, lumpy products due to coagulation, etc.) and a vinyl chloride resin, which causes formation of a poor sphere, and may enhance quality and processability of a vinyl chloride resin, by addressing the problem that an average distance between resin particles is decreased as polymerization proceeds, and thus, microparticles are generated due to excessive coagulation or friction between particles, and a method of mass-polymerizing the vinyl chloride resin. The method comprises additionally inputting a monomer to a reactor in which a monomer and an initiator are contained when a ratio of the monomer converted to a polymer is 30% to 70%.