Amorphous Polyetherimide Nonwoven Fabric for Electrical Insulation
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Solution Overview
Problem
Current nonwoven fabrics with flame retardancy lack electrical insulation, limiting their application in high-temperature environments and requiring improved manufacturing methods to achieve both properties effectively.
Innovation Solution
A nonwoven fabric composed of amorphous polyetherimide fibers with specific melt viscosity, fiber diameter, and treatment conditions, including a combination of elastic and metal rolls, to achieve both flame retardancy and electrical insulation, manufactured using methods like melt blown or spunbond techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a nonwoven fabric is made of extra-fine fibers using flash spinning, melt blown, or similar methods, then the fabric can be used for filter applications, but flame retardancy and heat resistance are insufficient making it unsuitable for high temperature use
Solution Approach 1:
The patent changes the material parameter from conventional polypropylene or polyester to polyetherimide (PEI) polymer, which inherently possesses high heat resistance and flame retardancy. By controlling the melt viscosity of PEI within 100-3000 Pas at 330°C and using specific spinning parameters, the invention achieves extra-fine fiber formation while maintaining excellent thermal stability and flame retardancy, resolving the contradiction between filter applicability and heat resistance
Solution Approach 2:
The patent creates a composite structure by forming a nonwoven fabric from PEI fibers with specific physical and chemical properties. The combination of PEI polymer's inherent flame retardant characteristics with the extra-fine fiber structure (1-10 μm diameter) produces a material that simultaneously achieves filter-grade fineness and high-temperature resistance, eliminating the need to choose between filtration capability and thermal stability
2Reliability
If techniques are used to manufacture nonwoven fabric from flame retardant polymer fibers, then flame retardancy is improved, but melt fracture or high melt tension occurs making it difficult to obtain extra-fine fibers with good productivity
Solution Approach 1:
The patent optimizes the melt viscosity parameter of PEI polymer to a specific range (100-3000 Pas at 330°C), which is critical for resolving the contradiction. This controlled viscosity range allows the polymer to be extruded as extra-fine fibers through spinning processes without experiencing melt fracture or excessive melt tension, while simultaneously maintaining excellent flame retardancy. The precise parameter control enables both high productivity and reliable flame retardant performance
Solution Approach 2:
The patent replaces conventional spinning methods that cause mechanical failure (melt fracture) with a controlled extrusion process using PEI's optimized rheological properties. By substituting the mechanical spinning approach with a process that leverages the polymer's specific melt characteristics, the invention achieves stable extra-fine fiber production with high productivity while preserving flame retardant properties
3Temperature
If a nonwoven fabric is made with spun lace method using amorphous PEI fibers, then flame retardancy and heat resistance are achieved, but the fiber diameter is relatively high (15 μm) and electrical insulation has not been achieved
Solution Approach 1:
The patent reduces the fiber diameter parameter from 15 μm to 1-10 μm by optimizing the extrusion and spinning parameters of amorphous PEI. This parameter change achieves finer fibers that can provide electrical insulation while maintaining the flame retardancy and heat resistance inherent to PEI material, thus resolving the contradiction between heat resistance and fiber fineness
4Length of moving object
If the fiber diameter is reduced to achieve extra-fine fibers, then potential for electrical insulation increases, but manufacturing difficulty increases due to melt fracture and high melt tension
Solution Approach 1:
The patent changes the material parameter from conventional polymers to PEI with specifically controlled melt viscosity (100-3000 Pas at 330°C). This parameter change enables the production of extra-fine fibers (1-10 μm) while avoiding melt fracture and high melt tension that plague conventional systems. The optimized viscosity parameter makes extra-fine fiber manufacturing easier and more productive while achieving the desired fiber diameter for electrical insulation
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 resulting nonwoven fabric exhibits enhanced flame retardancy and electrical insulation, suitable for wider applications including electrical insulating paper, with improved productivity and reduced environmental impact.
Implementation Method 1
continuously treating fibers between rolls arranged to face each other, at a temperature of 150 to 300°C
Implementation Method 2
a linear pressure of 100 to 500 kg/cm
Data Source
AI summary
Provided are a nonwoven fabric mainly composed of amorphous polyetherimide having a melt viscosity at 330°C of 100 to 3000 Pa·s, and satisfying conditions of: 1) an average fiber diameter of 0.5 to 5 µm; 2) an air permeability of more than or equal to 20 seconds/100 mL; and 3) a withstand voltage of more than or equal to 15 kV/mm, an insulating material using the nonwoven fabric, and a method for manufacturing the nonwoven fabric including continuously treating fibers between a pair of rolls at a temperature of 150 to 300°C and a linear pressure of 100 to 500 kg/cm.