Separator Coating Polymer Composition for Heat-Resistant Battery Films
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Solution Overview
Problem
Existing secondary battery separator coatings lack adequate heat resistance, air permeability, and adhesive properties, particularly when using acrylic water-soluble polymers with low reactive surfactant content or high acid group-containing monomer content.
Innovation Solution
A coating material for secondary battery separators comprising a water-soluble polymer with specific ratios of reactive surfactant and acidic group-containing vinyl monomer units, along with optional amide group-containing vinyl monomer, to enhance heat resistance, air permeability, and adhesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the reactive surfactant unit content is low relative to the water-soluble polymer, then the dispersibility is improved, but the heat resistance, air permeability, and adhesive properties are lowered
Solution Approach 1:
The invention changes the parameter of reactive surfactant unit content to a specific range (3-30 mass%) rather than using low content, and combines it with acid group-containing monomer units (3-19 mass%) to achieve a balance where dispersibility is maintained through surfactant units while heat resistance is improved through the specific composition ratio and glass transition temperature control
Solution Approach 2:
The invention creates a composite binder resin system combining water-soluble polymer units with reactive surfactant units and acid group-containing monomer units in specific ratios, forming a multi-component system that achieves synergistic effects for simultaneous improvement of dispersibility, heat resistance, and adhesive properties
2Strength
If the acid group-containing monomer unit content is high relative to the water-soluble polymer, then the adhesive properties are improved, but the heat resistance and air permeability are lowered
Solution Approach 1:
The invention optimizes the content parameter of acid group-containing monomer units to a specific range (3-19 mass%) rather than using high content, and balances it with reactive surfactant unit content to achieve adequate adhesive properties while maintaining heat resistance through controlled composition and glass transition temperature
Solution Approach 2:
The invention applies local quality by distributing different functional units (reactive surfactant units for dispersibility, acid group-containing units for adhesion) in specific ratios within the binder resin, creating regions with optimized local properties that collectively achieve overall performance balance
3Reliability
If the glass transition temperature of the water-soluble polymer is increased to improve heat resistance, then the heat resistance is improved, but the processing difficulty increases
Solution Approach 1:
The invention sets the glass transition temperature to a specific range (150°C or more) to ensure heat resistance while controlling the composition of reactive surfactant and acid group-containing monomer units to maintain processability, achieving a balance between thermal performance and manufacturing ease through optimized parameter combinations
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 coating material exhibits improved heat resistance, air permeability, and adhesive properties, enhancing the performance of secondary battery separators and the batteries they are used in.
Implementation Method 1
it has been known to introduce a reactive surfactant unit into the acrylic water-soluble polymer
Implementation Method 2
the water-soluble polymer has a glass transition temperature of 150° C. or more
Implementation Method 3
a second constituent unit derived from an acidic group-containing vinyl monomer
Data Source
AI summary
A raw material of a coating material for secondary battery separators contains a water-soluble polymer. The water-soluble polymer contains a first constituent unit derived from a reactive surfactant and a second constituent unit derived from an acidic group-containing vinyl monomer. A content ratio of the first constituent unit relative to the water-soluble polymer is 3% by mass or more and 30% by mass or less. A content ratio of the second constituent unit relative to the water-soluble polymer is 3% by mass or more and 19% by mass or less.