Conductive Resin Composition for Electromagnetic Shielding and Flame Retardancy
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Solution Overview
Problem
Existing electromagnetic shielding materials lack fire-resistance (flame-retardancy) and face a challenge in maintaining both excellent electromagnetic shielding properties and mechanical properties while keeping costs low, especially when increasing the content of coke powder reduces the effectiveness of flame retardants.
Innovation Solution
A conductive resin composition is developed, incorporating matrix resin, coke powder, carbon fiber, and a phosphorus-based foam-type flame retardant. The composition ensures that the coke powder content is between 5 mass% and 17 mass%, and the phosphorus-based flame retardant is at least 10 mass%, thereby preventing a decrease in flame retardancy and enhancing electromagnetic shielding properties without increasing the carbon fiber content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the content of coke powder is increased to improve electromagnetic shielding properties and reduce cost, then electromagnetic shielding performance improves, but the effectiveness of flame retardant decreases
Solution Approach 1:
The patent optimizes the content ratio of coke powder to phosphorus-based flame retardant, specifically setting coke powder at 2-20 parts by mass and phosphorus-based flame retardant at 80-70 parts by mass (total 100 parts). This parameter optimization ensures that the flame retardant maintains sufficient effectiveness while the coke powder provides adequate electromagnetic shielding, resolving the contradiction between shielding performance and flame retardancy.
Solution Approach 2:
The patent creates a composite resin composition combining matrix resin, coke powder, and phosphorus-based flame retardant in specific proportions. This composite structure allows the flame retardant to form a protective char layer that maintains its effectiveness even with the presence of conductive coke powder, while the coke powder provides electromagnetic shielding through its conductive network formation.
2Ease of manufacture
If the content of carbon fiber is reduced to lower cost, then cost performance improves, but mechanical properties may deteriorate
Solution Approach 1:
The patent replaces expensive carbon fiber with cheaper coke powder as the primary conductive filler. While coke powder has lower individual particle strength, the patent compensates by optimizing the overall composition with matrix resin and flame retardant, achieving acceptable mechanical properties at lower cost through this substitution strategy.
Solution Approach 2:
The patent adjusts the content of carbon fiber to 0.1-5 parts by mass (based on total 100 parts of all components), significantly reducing it from conventional levels. This parameter change lowers material cost while the electromagnetic shielding performance is maintained through the optimized coke powder content, and mechanical properties are balanced through the overall composition design.
3Reliability
If the content of phosphorus-based flame retardant is increased to maintain flame retardancy with high coke powder content, then flame retardancy is maintained, but the total content of conductive fillers must be limited
Solution Approach 1:
The patent optimizes the content of phosphorus-based flame retardant at 80-70 parts by mass (out of 100 parts total composition), ensuring sufficient flame retardancy through this parameter setting. Simultaneously, the coke powder content is controlled at 2-20 parts by mass, and carbon fiber at 0.1-5 parts by mass, maintaining the balance between flame retardancy and electromagnetic shielding effectiveness without excessive filler content.
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 conductive resin composition achieves excellent electromagnetic shielding properties, with an electric field shielding effect of 45 dB or more, and maintains high flame retardancy, as indicated by a limiting oxygen index of 36% or more, while maintaining excellent mechanical properties and keeping costs low.
Implementation Method 1
When a foam-type flame retardant (e.g., a phosphorus-based flame retardant) is used, foaming of the flame retardant is reduced in a conductive resin composition containing a large amount of coke powder
Implementation Method 2
the coke powder and the carbon fiber as electrically conductive fillers (conductive materials) form an aggregation structure thereby forming a network in the matrix resin even when the content of the coke powder is not less than 5 mass% and not more than 17 mass%. This forms a conductive path through which electricity passes in the matrix resin, causing a percolation phenomenon in which the electrical conductivity dramatically rises
Implementation Method 3
an electrically conductive function has been imparted to covering materials used for automobile parts, electronic devices, and the like to shield electromagnetic waves
Data Source
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AI summary
A conductive resin composition contains matrix resin, coke powder, carbon fiber, and a phosphorus-based flame retardant including (poly)phosphate. The volume mean particle diameter of the coke powder is not less than 1 µm and not more than 500 µm. The content of the coke powder in the conductive resin composition is not less than 5 mass% and not more than 17 mass%. The aspect ratio of the carbon fiber is not less than 3 and not more than 1700. The content of the carbon fiber in the conductive resin composition is not less than 0.5 mass% and not more than 5 mass%. The content of the phosphorus-based flame retardant in the conductive resin composition is not less than 10 mass%.