PVC-Reinforced Bipolar Membrane for High-Temperature Adhesion
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Solution Overview
Problem
Existing bipolar membranes face challenges in maintaining adhesiveness between cation-exchange and anion-exchange membranes, particularly under high-temperature conditions, leading to decreased current efficiency and membrane stability.
Innovation Solution
A bipolar membrane is produced by forming a cation-exchange membrane with a polyolefin reinforcing member and polyvinyl chloride, ensuring a high degree of adhesion through the use of polyvinyl chloride, which enhances compatibility with polar solvents and maintains membrane integrity during electrodialysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chlorinated polyolefin is used in the cation-exchange membrane or anion-exchange membrane to improve adhesiveness, then the adhesiveness between membranes is improved and stability is enhanced, but current efficiency deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the cation-exchange membrane by incorporating specific polymers (polyvinylidene fluoride, polyvinylidene chloride, or carboxymethyl cellulose) at controlled ratios (5-50% by mass), thereby achieving optimal balance between adhesiveness and current efficiency through parameter optimization rather than qualitative material change
Solution Approach 2:
The invention creates a composite membrane structure by combining the cation-exchange membrane containing specific adhesive polymers with the anion-exchange membrane, forming a bipolar membrane system where the cation-exchange membrane serves dual functions of ion exchange and adhesive bonding, thereby resolving the contradiction between adhesiveness and current efficiency
2Productivity
If membranes are used for extended periods or under high-temperature conditions, then production capacity is maintained, but membrane stability deteriorates due to peeling and swelling
Solution Approach 1:
The cation-exchange membrane contains polymers with inherent adhesive properties that enable the membrane to self-bond with the anion-exchange membrane without additional adhesives, and the polyolefin reinforcing member provides self-strengthening to resist swelling under operational stress, allowing extended use without external support
Solution Approach 2:
The polyolefin reinforcing member is embedded within the cation-exchange membrane structure in advance to provide mechanical strength and dimensional stability, cushioning against swelling forces and peeling stresses that occur during extended or high-temperature operation before damage can occur
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
The membrane achieves strong adhesion between the cation-exchange and anion-exchange membranes, suppressing anion leakage and maintaining excellent current efficiency even under high-temperature conditions.
Implementation Method 1
a step of forming a membrane of a cation-exchange resin that contains the polyvinyl chloride or of a cation-exchange resin precursor resin by polymerization-curing the polymerizable composition at a temperature of not lower than 100° C.
Implementation Method 2
a bipolar membrane in which a cation-exchange membrane and an anion-exchange membrane are joined to each other
Data Source
AI summary
A bipolar membrane in which a cation-exchange membrane and an anion-exchange membrane are joined to each other, wherein a leakage ratio of gluconic acid at 60° C. is not more than 1.0%, and the cation-exchange membrane is supported by a polyolefin reinforcing member and, further, contains a polyvinyl chloride.