Nonwoven fibrous web
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Solution Overview
Problem
Developers of insulation materials for EV battery applications face challenges in creating materials that are low in thermal conductivity, flame retardant, mechanically strong, and resistant to fiber shedding, while also being able to flex and compress to fit irregularly shaped enclosures and maintain structural integrity.
Innovation Solution
A nonwoven fibrous web composed of a flame retardant nonwoven fabric coated with ammonium polyphosphate or alkali metal silicate, featuring at least 60 wt% oxidized polyacrylonitrile fibers and up to 40 wt% reinforcing fibers with a melting temperature of 100-350°C, which are bonded together to form a cohesive web with enhanced strength and reduced fiber shedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flame retardant materials are used to protect EV batteries, then flame resistance is improved, but the materials become heavy and lose flexibility
Solution Approach 1:
The patent uses a composite nonwoven fabric structure combining oxidized polyacrylonitrile fibers (providing flame resistance) with reinforcing fibers having melting points of 100-350°C (providing mechanical strength and flexibility). This composite approach achieves UL-94V0 flame rating while maintaining flexibility and reducing weight compared to conventional flame retardant materials.
2Weight of moving object
If thermal insulation materials are made thin and lightweight for fuel economy, then weight is reduced, but mechanical strength and durability decrease
Solution Approach 1:
The nonwoven fabric incorporates reinforcing fibers with melting points of 100-350°C that provide mechanical strength and structural integrity. These reinforcing fibers work synergistically with the oxidized polyacrylonitrile fibers to deliver high mechanical strength in a thin, lightweight structure that maintains durability throughout the vehicle lifetime.
3Weight of moving object
If vehicle structures are made lighter to improve fuel efficiency, then fuel economy is improved, but noise from structural vibrations increases
Solution Approach 1:
The nonwoven fabric's porous structure and fibrous composition provide acoustic absorption capabilities that reduce airborne noise. The random orientation of fibers and interconnected voids create sound damping effects, allowing lightweight vehicle structures to maintain low noise levels without requiring heavy damping materials.
4Adaptability or versatility
If insulation materials are made to flex and compress for irregular enclosures, then adaptability is improved, but structural integrity and fiber shedding resistance worsen
Solution Approach 1:
The combination of oxidized polyacrylonitrile fibers with reinforcing fibers creates a composite structure that maintains structural integrity during flexing and compression. The reinforcing fibers prevent excessive deformation and reduce fiber shedding, allowing the material to adapt to irregular battery enclosures while maintaining compositional stability.
5Reliability
If flame retardant coatings are applied to nonwoven fabric, then flame resistance is improved, but fiber shedding increases
Solution Approach 1:
The reinforcing fibers in the composite nonwoven fabric provide structural support that binds the oxidized polyacrylonitrile fibers together, reducing fiber shedding. This composite structure achieves UL-94V0 flame rating while maintaining low fiber shedding through the synergistic interaction between fiber types.
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 solution provides effective thermal insulation, passes stringent flame tests, and maintains structural integrity, reducing the need for additional sealing and minimizing fiber shedding, thus addressing the technical challenges of EV battery insulation materials.
Implementation Method 1
a flame retardant nonwoven fabric coated with a fire retardant, wherein the fire retardant comprises ammonium polyphosphate or alkali metal silicate
Implementation Method 2
The reinforcing fibers can at least partially melt when heated to form a bonded web with enhanced strength
Implementation Method 3
Thermal insulators reduce heat transfer between structures either in thermal contact with each other or within range of thermal convection or radiation. These materials mitigate the effects of conduction, convection, and/or radiation
Data Source
Figure 1
AI summary
A nonwoven fibrous web includes a flame retardant nonwoven fabric coated with a fire retardant, wherein the fire retardant comprises ammonium polyphosphate or alkali metal silicate; and wherein the flame retardant nonwoven fabric has a first major surface and an opposed second major surface; a first nonwoven fabric covering at least a portion of the first major surface; and a second nonwoven fabric covering at least a portion of the second major surface. The first and second nonwoven fabrics each comprise oxidized polyacrylonitrile fibers and optional reinforcing fibers.