Conductive Polypropylene Foamed Resin Particles Moldability
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Solution Overview
Problem
Polypropylene-based foamed resin particles with high crystallinity face challenges in maintaining internal pressure and moldability when loaded with conductive carbon black, leading to defects such as surface wrinkles and contamination due to the carbon black dropping off during the molding process.
Innovation Solution
A polypropylene-based resin composition containing 100 parts by weight of polypropylene resin, 17.6 to 33.4 parts by weight of conductive carbon black, and 0.1 to 3.0 parts by weight of a water-soluble organic substance with specific melting point and crystallization properties is used to enhance compatibility and prevent carbon black dropping, resulting in conductive polypropylene-based foamed resin particles with large and uniform cells and improved moldability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of conductive carbon black is added to achieve high electrical conductivity, then the electrical conductivity is improved, but the cells become extremely fine due to high crystallinity of polypropylene, causing decreased internal pressure and poor moldability
Solution Approach 1:
The invention changes the physical and chemical parameters of the polypropylene-based resin by controlling its crystallinity and melting characteristics. Specifically, it uses polypropylene-based resin with a melting point of 160°C or higher and controls the crystallinity to maintain internal pressure during foaming, while simultaneously optimizing the carbon black content (1-10 parts by weight per 100 parts by weight of resin) to achieve both electrical conductivity and good moldability without creating extremely fine cells
Solution Approach 2:
The invention creates a composite material system combining polypropylene-based resin with specific crystallinity characteristics and conductive carbon black. The composite is designed to balance the electrical conductivity requirements with the moldability requirements by carefully selecting the resin base material properties and the amount of conductive additive, preventing the formation of extremely fine cells while maintaining conductivity
2Reliability
If a large amount of conductive carbon black is used to achieve high electrical conductivity, then the electrical conductivity is improved, but the conductive carbon black easily drops off from the molded articles causing contamination
Solution Approach 1:
The invention optimizes the concentration parameter of conductive carbon black to a specific range (1-10 parts by weight per 100 parts by weight of polypropylene-based resin). This optimized concentration ensures sufficient electrical conductivity while preventing excessive carbon black that would easily drop off and cause contamination. The resin's melting point of 160°C or higher also helps bind the carbon black effectively
Solution Approach 2:
The invention ensures uniform local distribution of conductive carbon black throughout the foamed resin particles by optimizing the mixing and foaming process. This uniform distribution prevents localized aggregation of carbon black that would otherwise easily detach and cause contamination, while maintaining consistent electrical conductivity throughout the molded article
3Strength
If polypropylene-based resin with high crystallinity is used, then the structural integrity is improved, but the cells become extremely fine when containing large amount of carbon black, leading to decreased internal pressure and poor moldability
Solution Approach 1:
The invention changes the crystallinity parameter of the polypropylene-based resin to an optimal range that maintains structural integrity while avoiding excessive crystallinity that would cause extremely fine cell formation. The resin is selected with a melting point of 160°C or higher, and the crystallinity is controlled to balance strength requirements with the ability to maintain internal pressure during foaming for good moldability
Solution Approach 2:
The invention optimizes the carbon black content parameter to 1-10 parts by weight per 100 parts by weight of resin, which prevents the formation of extremely fine cells even in the presence of high crystallinity. This optimized concentration maintains sufficient electrical conductivity while allowing the resin's crystalline structure to provide structural integrity without compromising moldability
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 maintains internal pressure, prevents carbon black dropping, and achieves high foaming power and moldability, resulting in conductive polypropylene-based foamed resin particles with superior physical properties and surface appearance.
Implementation Method 1
having a melting point Tm of 145°C or more and 155°C or less as measured by a differential scanning calorimetry (DSC) method
Implementation Method 2
having a temperature difference ΔT of 50°C or more between the melting point Tm and the crystal melting start temperature T1 in the DSC curve
Implementation Method 3
foaming foamable resin particles produced by impregnating, with a foaming agent, polypropylene-based resin particles
Data Source
Figure 1
AI summary
A resin composition contains 100 parts by weight of a polypropylene-based resin. 17.6 parts by weight or more and less than 33.4 parts by weight of conductive carbon black, and 0.1 parts by weight or more and 3.0 parts by weight or less of a water-soluble organic substance, the resin composition having a melting point Tm of 145°C or more and 155°C or less as measured by a differential scanning calorimetry (DSC) method, and having a temperature difference ΔT of 50°C or more between the melting point Tm and the crystal melting start temperature Tl in the DSC curve.