Polyimide Film Modulus for Graphite Sheet Production

Solution Overview

Problem

The production of graphite sheets from polyimide films in a roll type state often results in deformation, rupture, or damage due to heat-induced shrinkage, leading to high defect rates and reduced productivity in commercial mass production.

Innovation Solution

A polyimide film with a modulus of 2.7 GPa or more, produced by imidizing a polyamic acid derived from specific dianhydride and diamine monomers, and incorporating fillers with different average particle diameters, is used to minimize deformation and rupture during carbonization and graphitization, thereby enhancing mechanical rigidity and reducing defect rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If polyimide film is heat-treated in a wound roll state for carbonization and graphitization, then production efficiency is improved and process is simplified, but film rupture and damage occur due to accumulated shrinkage stress

Engineering Contradiction:

Improveproduction efficiencyVSAvoidfilm integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-modifying the polyimide film structure before heat treatment. Specifically, the film is subjected to a pre-treatment process that introduces controlled micro-voids or adjusts the molecular structure in advance, allowing the film to better accommodate subsequent thermal shrinkage during carbonization and graphitization without rupturing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by adjusting the thermal treatment parameters, including heating rate, temperature profile, and holding time. The heat treatment is conducted in multiple stages with controlled temperature increases, allowing gradual structural transformation that reduces internal stress accumulation and prevents film rupture during roll-type carbonization.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If polyimide film is cut and processed individually instead of in roll type, then film rupture is reduced, but production time and labor cost increase

Engineering Contradiction:

Improvefilm integrityVSAvoidproduction time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-modifying the polyimide film structure before heat treatment. Specifically, the film is subjected to a pre-treatment process that introduces controlled micro-voids or adjusts the molecular structure in advance, allowing the film to better accommodate subsequent thermal shrinkage during carbonization and graphitization without rupturing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by adjusting the thermal treatment parameters, including heating rate, temperature profile, and holding time. The heat treatment is conducted in multiple stages with controlled temperature increases, allowing gradual structural transformation that reduces internal stress accumulation and prevents film rupture during roll-type carbonization.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If high modulus polyimide film (≥2.7 GPa) is used to prevent rupture, then film integrity is improved, but film flexibility and processability may be reduced

Engineering Contradiction:

Improvefilm integrityVSAvoidfilm processability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs parameter changes by adjusting the thermal treatment parameters, including heating rate, temperature profile, and holding time. The heat treatment is conducted in multiple stages with controlled temperature increases, allowing gradual structural transformation that reduces internal stress accumulation and prevents film rupture during roll-type carbonization.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies composite materials by combining polyimide with specific additives or creating a composite structure within the film. The high modulus is achieved through compositional modification rather than simply increasing crosslinking density, which helps maintain film flexibility and processability while improving heat resistance and structural integrity during carbonization.

Inventive Principle:

Principle #40Composite materials

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 solution effectively reduces the percentage of defective products, saves manpower and time, and enables effective commercial mass production of graphite sheets by preventing deformation and rupture during the production process.

Implementation Method 1

the graphite sheet is produced by carbonizing and graphitizing long film-shaped polyimide films through heat treatment in different temperature ranges, respectively

Methodology Applied

Scientific EffectCarbonization: Pyrolysis

Implementation Method 2

the graphite sheet is produced by carbonizing and graphitizing long film-shaped polyimide films through heat treatment in different temperature ranges, respectively

Methodology Applied

Scientific EffectGraphitization: Heat Treatment

Implementation Method 3

heat applied during the carbonizing and graphitizing process causes shrinkage to the polyimide films

Methodology Applied

Scientific EffectThermal shrinkage: Thermal Contraction

Data Source

PatentUS11655336B2Polyimide film for preparing roll type graphite sheet

Publication Date: 2023.05.23 SKCKOLON

AI summary

The present invention provides a polyimide film for a roll type graphite sheet prepared by imidizing a polyamic acid formed by a reaction of a dianhydride monomer and a diamine monomer, where the polyimide film has a modulus of 2.7 GPa or more.