Flexible PVDF Copolymer Composition for Adhesive Battery Films
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Solution Overview
Problem
Fluoropolymer copolymers used in flexible applications, such as batteries, face challenges in maintaining high chemical resistance and mechanical properties while achieving good flexibility and adhesion to metal substrates, as the crystallinity of these copolymers decreases with modifications from monomers other than VDF.
Innovation Solution
A semi-crystalline vinylidene fluoride copolymer comprising recurring units from hydrophilic (meth)acrylic monomers and perhalogenated monomers, with specific mole percentages, that maintains high intrinsic viscosity and adhesion to metal substrates, allowing for flexible films suitable for dynamic bending applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If VDF copolymers are modified with monomers different from VDF to improve flexibility and adhesion, then flexibility and adhesion are improved, but crystallinity and chemical resistance decrease
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar percentages of different monomers (VDF, HF, MA) to optimize the balance between flexibility and chemical resistance. Specifically, limiting HF to 0.5-5.0 mol% and MA to 0.05-2.0 mol% creates the desired flexibility while preserving sufficient crystallinity for chemical resistance
Solution Approach 2:
The patent creates a composite copolymer structure combining four different monomer units (VDF, HF, MA, and a fourth comonomer) in specific proportions. This composite approach allows each monomer to contribute its beneficial properties: VDF provides chemical resistance, HF enhances flexibility, MA improves adhesion, and the fourth comonomer fine-tunes the crystallinity-flexibility balance
2Strength
If VDF copolymers are modified with monomers different from VDF to improve adhesion to metal substrates, then adhesion is improved, but crystallinity and mechanical properties decrease
Solution Approach 1:
The patent optimizes adhesion by controlling the molar percentage of hydrophilic (meth)acrylic monomer (MA) within 0.05-2.0 mol%. This precise parameter control ensures sufficient polarity for metal substrate adhesion while maintaining the crystalline structure necessary for mechanical strength
Solution Approach 2:
The patent applies local quality by introducing polar MA monomer units at specific concentrations (0.05-2.0 mol%) within the predominantly non-polar VDF matrix. This creates localized polar regions that enhance metal adhesion while the bulk material retains its crystalline mechanical properties
3Ease of operation
If VDF copolymers are modified with higher amounts of comonomers to improve flexibility, then flexibility is improved, but crystallinity and chemical resistance decrease
Solution Approach 1:
The patent employs parameter changes by strictly limiting the total comonomer content (HF + MA + fourth comonomer) to maintain crystallinity above 30%. The specific ranges (HF: 0.5-5.0 mol%, MA: 0.05-2.0 mol%) are optimized to provide flexibility while preserving the crystalline structure
Solution Approach 2:
The patent enables the copolymer to self-regulate its crystallinity through the synergistic interaction of monomer units. The VDF units form crystalline domains that automatically maintain structural integrity, while the limited HF and MA units provide flexibility without disrupting the overall crystalline order
Data Source
AI summary
The present invention pertains to vinylidene fluoride copolymers having improved flexibility, said copolymers comprising recurring units derived from hydrophilic (meth)acrylic monomers and from perhalogenated monomers, to a process for the manufacture of said copolymers, and to their use in applications where outstanding flexibility is required.