Expanded Polypropylene Resin Particles with Coarse Carbon Black
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Solution Overview
Problem
Conventional polypropylene resin-based in-mold expansion-molded products face challenges in achieving both excellent electrical conductivity and flame retardancy, particularly when using inorganic foaming agents, which typically deteriorate flame retardancy.
Innovation Solution
The development of expanded polypropylene resin particles with a specific range of electrically conductive carbon black and a cell diameter enlarging agent, such as polyethylene glycol, when using carbon dioxide as a foaming agent, enhances the average cell diameter and improves flame retardancy without the need for additional flame retardants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrically conductive carbon black is added in an amount of not less than 10 wt% to achieve excellent electrical conductivity, then electrical conductivity is improved, but flame retardancy deteriorates
Solution Approach 1:
The invention changes the particle size parameter of carbon black from conventional fine particles to coarse particles with a specific surface area of 5 m²/g or less. This parameter change allows achieving excellent electrical conductivity with reduced carbon black content, thereby improving flame retardancy while maintaining conductivity
Solution Approach 2:
The invention creates a composite material system combining coarse carbon black particles with polypropylene resin and foaming agents. This composite structure achieves synergistic effects where the coarse carbon black provides conductivity pathways while the resin matrix and foaming agent structure maintain flame retardancy
2Ease of manufacture
If an inorganic foaming agent such as carbon dioxide is used to produce expanded polypropylene resin particles, then cost and environmental friendliness are improved, but flame retardancy deteriorates notably
Solution Approach 1:
The invention changes the carbon black particle size parameter to coarse particles, which compensates for the flame retardancy deterioration caused by using inorganic foaming agents. The reduced specific surface area of coarse carbon black particles reduces their negative impact on flame retardancy while maintaining conductivity
Solution Approach 2:
The invention develops a composite formulation combining inorganic foaming agents with coarse carbon black and polypropylene resin. This composite system achieves synergistic effects where the inorganic foaming agent provides cost and environmental benefits while the coarse carbon black structure maintains both conductivity and acceptable flame retardancy
3Ease of manufacture
If coloring carbon black is used to color polypropylene resin-based in-mold expansion-molded products, then coloring performance is improved, but flame retardancy deteriorates
Solution Approach 1:
The invention changes from using fine coloring carbon black to coarse carbon black particles for coloring applications. This parameter change reduces the specific surface area, which lessens the negative impact on flame retardancy while still achieving adequate coloring performance and electrical conductivity
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 approach results in polypropylene resin-based in-mold expansion-molded products that exhibit improved flame retardancy while maintaining excellent electrical conductivity, passing high-level flame retardancy standards like UL94, and possessing suitable volume resistivity values.
Implementation Method 1
a polypropylene resin composition containing a polypropylene resin and electrically conductive carbon black having a specific dibutyl phthalate absorption amount
Implementation Method 2
an electrically conductive polypropylene resin-based in-mold expansion-molded product which contains electrically conductive carbon black
Data Source
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AI summary
Provided are expanded polypropylene resin particles from which a polypropylene resin-based in-mold expansion-molded product is obtainable, the polypropylene resin-based in-mold expansion-molded product being excellent in electrical conductivity and particularly having improved in flame retardancy with no use of a flame retardant. Expanded polypropylene resin particles obtainable by expanding polypropylene resin particles containing a polypropylene resin composition which contains electrically conductive carbon black in an amount in a range of not less than 11 parts by weight and not more than 25 parts by weight with respect to 100 parts by weight of polypropylene resin, the electrically conductive carbon black having a dibutyl phthalate absorption amount in a range of not less than 300 cm3/ 100 g and not more than 600 cm3/ 100 g, have an average cell diameter in a range of more than 0.16 mm and not more than 0.35 mm.