Polypropylene-COP Capacitor Film for Heat and Breakdown Strength
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Solution Overview
Problem
Existing polypropylene capacitor compositions face challenges in achieving high temperature resistance without compromising mechanical properties and electrical breakdown strength, as previous solutions have sacrificed stiffness and low shrinkage to enhance temperature resistance.
Innovation Solution
A polypropylene composition comprising 83 to 87 wt.% of polypropylene homopolymer and 13 to 17 wt.% of cyclic olefin polymer, with cyclic olefin units in specific weight ranges, is developed using melt-blending to achieve improved mechanical and electrical properties, including high isotacticity, low ash content, and controlled glass transition temperature, resulting in a biaxially oriented film with enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polypropylene is combined with cyclic olefin copolymers to increase temperature resistance, then the maximum operating temperature is improved, but mechanical properties such as stiffness and low shrinkage are sacrificed
Solution Approach 1:
The invention changes the compositional parameters by specifying precise weight ratios (83-87 wt% polypropylene homopolymer and 13-17 wt% cyclic olefin polymer) and specific glass transition temperature ranges (120-170°C) to achieve optimal balance between temperature resistance and mechanical properties
Solution Approach 2:
The invention creates a composite material system combining polypropylene homopolymer with cyclic olefin polymer (such as ethylene norbornene copolymer) where the specific composition and molecular structure of each component work synergistically to provide both high temperature resistance and maintained mechanical strength
2Temperature
If polypropylene is combined with composite rubber powder to address temperature resistance, then the temperature resistance is improved, but the composition complexity and manufacturing difficulty increase
Solution Approach 1:
The invention extracts and eliminates the complex multi-component rubber powder system (silicone rubber + nucleating agent + irradiation vulcanization) and replaces it with a simpler cyclic olefin polymer that inherently provides temperature resistance through its glass transition properties, reducing compositional complexity
Solution Approach 2:
The invention uses commercially available cyclic olefin polymers with defined glass transition temperatures as ready-to-use modifiers, eliminating the need for complex in-situ synthesis or multi-step processing required by rubber powder systems
Data Source
Figure 1(a)~1(c)
AI summary
The present invention relates to a composition comprising 83 to 87 wt.% of a polypropylene homopolymer and 13 to 17 wt.% of a cyclic olefin polymer comprising cyclic olefin units, wherein the content of the cyclic olefin units is in a range of from 73 to 77 wt.% or in a range from 82 to 86 wt.%, based on the total weight of the cyclic olefin polymer. The present invention is, furthermore, directed to a film comprising the composition, wherein the film may be a cast film or a biaxially oriented film. Apart from that, a capacitor comprising the biaxially oriented film is provided.