Bipolar Membrane Adhesion via Chlorinated Polyolefin
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Solution Overview
Problem
Conventional bipolar membranes have insufficient adhesion between cation-exchange and anion-exchange membranes, leading to peeling issues during high-temperature electrodialysis, which limits their industrial application and increases manufacturing costs.
Innovation Solution
Incorporating chlorinated polyolefin into at least one of the ion-exchange membranes or the interface between them, with a chlorine content of 20-80% by weight, to enhance adhesion and heat resistance without increasing membrane voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesion methods (polyethyleneimine/epichlorohydrin mixture, ion exchange adhesive, paste-like ion-exchange resin) are used to improve adhesion between membranes, then adhesion is improved, but bipolar voltage becomes too high for industrial use
Solution Approach 1:
The invention changes the chemical composition parameters of the interface layer by incorporating specific compounds (tertiary amines, quaternary ammonium compounds, or chlorinated polyolefin) with defined molecular structures and properties. This parameter change enables the interface layer to provide both adhesion function and low electrical resistance, resolving the contradiction between improved adhesion and reduced bipolar voltage
Solution Approach 2:
The invention introduces an intermediary substance (adhesive compound) at the interface between the anion-exchange membrane and cation-exchange membrane. This intermediary layer with thickness of 1-50 μm mediates between the two membranes, providing adhesion while maintaining low electrical resistance through its specific chemical composition (tertiary amine, quaternary ammonium compound, or chlorinated polyolefin), thus preventing the voltage increase that would result from direct membrane contact
2Productivity
If membranes are used for extended period electrodialysis, then acid and alkali production continues, but membranes swell and peel off
Solution Approach 1:
The invention applies beforehand cushioning by incorporating swelling-resistant compounds (tertiary amines, quaternary ammonium compounds, or chlorinated polyolefin) into the interface layer before the membranes are subjected to extended electrodialysis operation. This pre-established protective interface layer prevents the swelling and peeling that would otherwise occur during prolonged use, ensuring continuous reliable operation
Solution Approach 2:
The invention uses composite materials by creating an interface layer that combines the anion-exchange membrane, cation-exchange membrane, and adhesive compound (tertiary amine, quaternary ammonium compound, or chlorinated polyolefin) into a composite structure. This composite interface layer integrates the functional properties of all components, providing both adhesion strength and swelling resistance for extended operational reliability
3Productivity
If electrodialysis is conducted at high temperature to improve production efficiency, then productivity increases, but membrane adhesion deteriorates and peeling occurs
Solution Approach 1:
The invention changes the thermal stability parameters of the interface layer by selecting adhesive compounds (tertiary amines, quaternary ammonium compounds, or chlorinated polyolefin) with high thermal resistance. This parameter change enables the interface layer to maintain adhesion strength at elevated temperatures, allowing high-temperature electrodialysis operation without membrane peeling while preserving production efficiency
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 bipolar membrane exhibits improved adhesion and heat resistance, allowing stable electrodialysis under high-temperature conditions without peeling, and maintains low bipolar voltage, enabling efficient acid and alkali production on an industrial scale.
Implementation Method 1
at least one of the ion-exchange membranes has a chlorinated polyolefin blended with it... featuring adhesion or greatly improved peeling resistance between the cation-exchange membrane and the anion-exchange membrane
Implementation Method 2
has a function for splitting water into protons and hydroxide ions... a water splitting voltage (V') required for splitting water in the interface between the cation-exchange resin layer and the anion-exchange resin layer
Data Source
AI summary
To provide a bipolar membrane featuring improved adhesion between an anion-exchange membrane and a cation-exchange membrane without accompanied by an increase in the membrane voltage. [Means for Solution] A bipolar membrane comprising a cation-exchange membrane and an anion-exchange membrane joined together facing each other, wherein at least one of the ion exchange membranes contains a chlorinated polyolefin.