Extruded capacitor films with high temperature performance, methods of manufacture, and articles containing the same
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Solution Overview
Problem
There is a need for high temperature capacitor films with excellent electrical properties, specifically high dielectric breakdown strength, that can be manufactured by extrusion on a commercial scale, as existing high temperature polymers suffer from undesirable dielectric breakdown strength at room temperature and are difficult to produce as thin, high-quality films.
Innovation Solution
A composition comprising a high heat copolycarbonate with a specific carbon-to-hydrogen-oxygen-fluorine ratio, combined with an organic slip agent and a roughening agent, is used to create ultra-thin, high temperature capacitor films via extrusion, achieving good flow properties, mechanical strength, and electrical properties, including high dielectric breakdown strength and self-clearing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature polymers are used to achieve high operating temperature capability, then the glass transition temperature is improved, but the dielectric breakdown strength deteriorates
Solution Approach 1:
The patent uses a composite material system consisting of polycarbonate as the base polymer combined with specific additives (epoxidized soybean oil at 0.01-5 wt% and metal stearates at 0.01-5 wt%). This composite approach allows the material to achieve both high glass transition temperature (≥150°C) and improved dielectric breakdown strength, resolving the contradiction between temperature resistance and electrical reliability.
2Volume of moving object
If thin films are manufactured by extrusion to reduce capacitor size, then the volumetric energy density is improved, but the manufacturing difficulty increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the extrusion material by incorporating epoxidized soybean oil and metal stearates, which change the rheological properties and surface characteristics of the polymer. These parameter changes enable the extrusion process to successfully produce thin films (≤10 μm) with controlled surface roughness and reduced sticking, thereby improving manufacturability while maintaining small capacitor volume.
3Quantity of substance
If thin films are produced to maximize energy storage density, then the film thickness is reduced, but the handling and shipping difficulty increases
Solution Approach 1:
The patent introduces metal stearates (such as calcium stearate, zinc stearate, or barium stearate) as intermediary substances that migrate to the film surface during extrusion. These compounds act as release agents and anti-sticking intermediaries between the thin film and handling surfaces, enabling easy handling and shipping of ultra-thin films (≤10 μm) while maintaining high energy storage density through minimal thickness.
Data Source
AI summary
A composition includes 65.0-99.85 wt % of a high heat copolycarbonate, the high heat copolycarbonate further having a number ratio of carbon atoms to a total of hydrogen, oxygen, and fluorine atoms of less than 1.12, preferably from 0.83 to less than 1.12; 0.05-0.5 wt % of a first roughening agent; and 0.1-15.0 wt % of an organic slip agent, wherein the organic slip agent comprises pentaerythritol tetrastearate, dipentaerythritol hexastearate, glycerol tristearate, high density poly(ethylene), polymethylpentene, a poly(carbonate-siloxane), or a combination thereof; wherein each amount is based on the total weight of the composition and totals 100 wt %.