Method for preparing graphite sheet
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Solution Overview
Problem
The polymer graphitization method struggles to produce thick graphite films and is costly due to the use of expensive polyimide films, limiting its application in achieving high thermal conductivity and large thickness efficiently.
Innovation Solution
A method involving a substrate coated with a liquid resin, solvent, dehydrating agent, and catalyst, followed by thermal treatment, where primary and secondary coatings are applied with pressure to graphitize the substrate, reducing manufacturing costs and enhancing thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the polymer graphitization method is used, then thermal conductivity and electrical conductivity are improved, but the film thickness is limited and manufacturing cost increases
Solution Approach 1:
The invention changes the chemical composition parameters of the polymer film by incorporating specific additives (metal salts, metal organic compounds, or metal particles) to enable thick film formation while maintaining high thermal conductivity after graphitization. This allows achieving both thick films and high thermal conductivity that were previously contradictory
Solution Approach 2:
The invention creates a composite polymer film structure by combining base polymer materials with metal-containing compounds or particles. This composite approach enables the film to achieve both mechanical integrity for thick sections and high thermal conductivity through the metal components that enhance graphitization, resolving the contradiction between thickness and thermal conductivity
2Reliability
If expensive polyimide film is used for graphitization, then thermal conductivity is improved, but manufacturing cost increases
Solution Approach 1:
The invention replaces expensive polyimide film with cheaper polymer films (such as polyvinylidene fluoride, polyacrylonitrile, or cellulose-based films) that can be readily graphitized when containing metal additives. This substitution significantly reduces raw material costs while maintaining the ability to achieve high thermal conductivity through controlled graphitization of the cheaper polymer matrix
Solution Approach 2:
The invention changes the material selection parameters by identifying and utilizing alternative polymer substrates that are inherently cheaper than polyimide but can still achieve high thermal conductivity when doped with metal compounds. This parameter change in material composition enables cost-effective production without sacrificing thermal performance
3Length of stationary object
If graphite expansion method is used, then film thickness can be increased, but residual acids and weak strength problems occur
Solution Approach 1:
The invention converts the harmful acid treatment step of the graphite expansion method into a beneficial process by using metal salts or metal organic compounds as dehydrating agents during thermal treatment. These compounds facilitate water removal and graphitization without leaving harmful residual acids, while still enabling thick film formation. The metal additives promote controlled decomposition and carbonization that achieves graphitization without the need for aggressive acid expansion
Solution Approach 2:
The invention substitutes the chemical mechanism of acid expansion with a thermal-decomposition-based graphitization mechanism. Instead of using concentrated sulfuric acid to expand graphite interlayers, the invention uses thermal treatment of metal-containing polymer composites where metal compounds act as dehydrating agents and catalysts for graphitization. This mechanical/thermal substitution eliminates the need for harmful chemical expansion while achieving similar or better structural outcomes
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
This method produces a graphite sheet with high thermal conductivity and large thickness in a cost-effective manner, utilizing inexpensive fiber substrates and ensuring a dense structure by removing bubbles, thus improving thermal conductivity and reducing resistance.
Implementation Method 1
thermally treating the coated substrate to graphitize it
Implementation Method 2
the coating liquid comprises a liquid resin, a solvent, a dehydrating agent, and a catalyst
Implementation Method 3
the coating liquid comprises a liquid resin, a solvent, a dehydrating agent, and a catalyst
Data Source
AI summary
The embodiment relates to a method for preparing a graphite sheet having a high thermal conductivity at a low cost without using an expensive polyimide film.