Polypropylene film, metal membrane layered film, and film capacitor
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Solution Overview
Problem
Polypropylene films used in capacitors face challenges in maintaining breakdown voltage and reliability under high temperature environments exceeding 110°C, with issues related to molecular chain relaxation, surface orientation, and structural instability during thermal processing.
Innovation Solution
A polypropylene film with controlled crystallite size difference and shrinkage stress, optimized through specific stretching and heat treatment conditions, ensuring uniform molecular alignment and reduced thermal shrinkage, enhancing structural stability and breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polypropylene film is used in high temperature environment exceeding 110°C, then capacitor performance is improved, but molecular chain relaxation occurs and structural stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite size of the α crystal (110) plane to 10 nm or less and adjusting the stretching conditions to achieve specific orientation degrees. These parameter optimizations enable the film to maintain structural stability at high temperatures exceeding 110°C, resolving the contradiction between operating temperature and structural stability.
Solution Approach 2:
The patent uses composite material strategies by combining polypropylene resin with specific crystal structures and surface characteristics. The controlled crystallite size and orientation create a composite-like structure within the polypropylene matrix that enhances thermal stability and prevents molecular chain relaxation at high temperatures.
2Volume of moving object
If film thickness is reduced to achieve miniaturization, then capacitor size is reduced, but breakdown voltage and reliability deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the crystallite size to 10 nm or less and optimizing the stretching conditions to achieve specific orientation degrees. These parameter optimizations enhance the dielectric properties and breakdown voltage of thin films, enabling miniaturization while maintaining reliability.
Solution Approach 2:
The patent replaces mechanical reinforcement with structural optimization at the nanoscale. Instead of using thicker films or additional layers to improve breakdown voltage, the invention uses controlled crystallite size and molecular orientation to achieve high breakdown voltage in thin films through structural design rather than mechanical means.
3Stability of the object's composition
If stretching ratio is increased to improve molecular alignment, then orientation is improved, but film uniformity and surface characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the stretching ratio and temperature conditions to achieve the desired balance between molecular alignment and film uniformity. The specific parameter ranges for stretching ratio and temperature are carefully controlled to prevent excessive alignment that would compromise uniformity.
Solution Approach 2:
The patent applies partial action by using a moderate stretching ratio that achieves sufficient molecular alignment without over-stretching the film. This partial stretching approach maintains film uniformity and surface characteristics while still improving molecular alignment to the necessary degree.
4Stability of the object's composition
If heat treatment is applied to stabilize structure, then thermal stability is improved, but manufacturing complexity and process control difficulty increase
Solution Approach 1:
The patent applies parameter changes by optimizing heat treatment temperature and time parameters to achieve thermal stability with minimal process complexity. The specific temperature and time ranges are selected to stabilize the crystal structure without requiring complex multi-stage heat treatment processes.
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 film exhibits improved breakdown voltage and reliability under high temperature conditions, minimizing leakage current and capacitance reduction, with reduced thermal shrinkage and enhanced processability.
Implementation Method 1
an absolute value of a difference between a crystallite size obtained by scanning an α crystal (110) plane by wide angle X-ray diffraction in a main alignment direction and a crystallite size obtained by scanning the α crystal plane in a direction orthogonal to the main alignment direction is 3.0 nm or less
Implementation Method 2
optimized through specific stretching and heat treatment conditions, ensuring uniform molecular alignment and reduced thermal shrinkage
Implementation Method 3
a shrinkage stress in a machine direction at 135° C. in a heating process at a temperature elevation rate of 10° C./min in thermomechanical analysis is 2.0 MPa or less
Data Source
AI summary
There is provided a polypropylene film that has excellent reliability and withstand voltage characteristics in high temperature environments when used in high voltage capacitors, that has a structure with excellent stability against heat and is suitable for applications in capacitors or the like to be used at high temperatures and high voltages, and that has excellent processability and does not wrinkle during a conveyance process including a vapor deposition process. The polypropylene film has an absolute value of a difference between a crystallite size obtained by scanning an a crystal (110) plane by wide angle X-ray diffraction in a main alignment direction and a crystallite size obtained by scanning an a crystal plane in a direction orthogonal to the main alignment direction is 3.0 nm or less, and a shrinkage stress in a machine direction (SF 135 MD) is 2.0 MPa or less at 135° C. in a heating process at a temperature elevation rate of 10° C./min in thermomechanical analysis (TMA).