Multilayer Polypropylene Capacitor Film to Suppress Nucleating Agent Bleeding

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Solution Overview

Problem

Existing polypropylene films for capacitors fail to adequately enhance high-temperature dielectric breakdown voltage (BDV) and are prone to nucleating agent bleeding, which contaminates production equipment.

Innovation Solution

A multilayer polypropylene film comprising a base layer with a propylene homopolymer and a polymer-based α-crystal nucleating agent, and a front or back layer composed of a propylene-based polymer, both of which are stretched, to suppress nucleating agent bleeding and improve high-temperature BDV.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an organic nucleating agent is added to polypropylene to improve high-temperature dielectric breakdown voltage, then the high-temperature BDV is improved, but the nucleating agent bleeds out to the surface and contaminates production equipment

Engineering Contradiction:

Improvehigh-temperature dielectric breakdown voltageVSAvoidnucleating agent bleeding

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The film is divided into multiple layers: a base layer containing the nucleating agent for high-temperature BDV improvement, and surface layers (front and/or back layers) composed of propylene-based polymer without nucleating agent to prevent bleeding. This segmentation isolates the harmful nucleating agent to the base layer while maintaining its functional benefit, preventing contamination of production equipment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The surface layers act as intermediary barriers between the nucleating agent in the base layer and the external environment (production equipment). These intermediate layers prevent direct contact and bleeding of the nucleating agent while allowing the base layer to maintain its high-temperature dielectric breakdown voltage properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If the film is miniaturized and capacity is increased for high output applications, then the capacitor performance is improved, but the use temperature increases and voltage endurance at high temperature becomes insufficient

Engineering Contradiction:

Improveoutput capacityVSAvoidvoltage endurance at high temperature

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The film uses a composite structure combining propylene homopolymer (base layer) with polymer-based α-crystal nucleating agent to achieve both high output capacity and high-temperature voltage endurance. The composite material approach allows the film to be miniaturized for high capacity while the nucleating agent enhances crystallinity and thermal stability for voltage endurance at elevated temperatures.

Inventive Principle:

Principle #40Composite materials

3Reliability

If a single-layer film with nucleating agent is used to improve high-temperature BDV, then the dielectric breakdown voltage is improved, but the bleeding of nucleating agent contaminates production equipment

Engineering Contradiction:

Improvehigh-temperature dielectric breakdown voltageVSAvoidproduction equipment contamination

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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 multilayer film effectively suppresses nucleating agent bleeding and enhances high-temperature BDV while providing blocking resistance, ensuring long-term reliability and performance.

Implementation Method 1

a base layer composed of a propylene polymer composition containing a propylene homopolymer (X) and 0.0001 to 0.05 mass % of a polymer-based α-crystal nucleating agent (C)

Methodology Applied

Scientific EffectNucleation: Nucleation

Implementation Method 2

both of the base layer, and the front layer or the back layer are stretched

Methodology Applied

Scientific EffectDeformation: Deformation

Data Source

PatentUS12384908B2Multilayer polypropylene film for capacitor

Publication Date: 2025.08.12 PRIME POLYMER CO LTD

AI summary

An object of the present invention is to provide a film for a capacitor such that the film excels in high-temperature dielectric breakdown voltage (high-temperature BDV) and has blocking resistance, and bleeding-out of, for instance, a nucleating agent is suppressed even after long-term storage. The present invention pertains to a multilayer polypropylene film for a capacitor, the film including a base layer composed of a propylene polymer composition containing a propylene homopolymer (X) and 0.0001 to 0.05 mass % of a polymer-based α-crystal nucleating agent (C), and a front layer or a back layer composed of a propylene-based polymer (Y) on at least one surface of the base layer, wherein the base layer and the front layer or back layer are stretched.