Modified Polyvinyl Alcohol Dispersant for PVC Suspension Polymerization
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Solution Overview
Problem
Conventional polyvinyl chloride (PVC)-based resin production methods, such as suspension polymerization, face challenges with instability and particle size issues due to limited stabilization by conventional polyvinyl alcohol-based polymers, resulting in larger particle diameters and coarse particles.
Innovation Solution
A modified polyvinyl alcohol-based polymer with a specific saponification degree of 67% to 78% and modification rate of 0.02% to 1.5% is introduced, featuring an isocyanate-modified structure with a grafting moiety comprising an alkenyl group, enhancing dispersion stability and controlling particle diameter in suspension polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polyvinyl alcohol-based polymer is used as dispersant for suspension polymerization, then the polymerization process can be maintained, but the dispersion stability is limited and the resulting PVC resin has larger particle diameter and many coarse particles
Solution Approach 1:
The patent modifies the polyvinyl alcohol polymer by controlling the saponification degree (60-85 mol%) and introducing specific side chain structures with hydrophobic groups. These parameter changes in polymer composition and structure enhance the dispersant's ability to stabilize suspension polymerization, resulting in improved particle diameter control and reduced coarse particles in the PVC resin
Solution Approach 2:
The patent creates a composite polymer structure by combining polyvinyl alcohol backbone with grafted side chains containing hydrophobic groups (such as alkyl or aryl groups). This composite structure provides both hydrophilic properties for water solubility and hydrophobic interactions for better interface stabilization with vinyl chloride monomer droplets, thereby improving dispersion stability and particle size control
2Reliability
If polyvinyl alcohol-based polymer is used as dispersant, then suspension polymerization can proceed, but the stabilization effect is limited requiring additional dispersants
Solution Approach 1:
The modified polyvinyl alcohol polymer performs multiple functions simultaneously: it acts as a dispersant to stabilize monomer droplets, a protective colloid to prevent particle aggregation, and a chain transfer agent to control polymerization kinetics. This multi-functionality eliminates the need for additional dispersants while maintaining suspension polymerization stability
Data Source
AI summary
The present disclosure provides a modified polyvinyl alcohol-based polymer, which comprises a modifying monomer unit represented by Formulawherein, X is a moiety comprising an alkenyl group, and the modified polyvinyl alcohol-based polymer has a saponification degree of 67 mol % to 78 mol % and a modification rate of 0.02 mol % to 1.5 mol %. The modified polyvinyl alcohol-based polymer is suitable to be used as a dispersant for suspension polymerization, to make the obtained polyvinyl chloride-based resin have reduced particle diameter and few coarse particles.