Polyolefin Airbag Cover Material Ionic Crosslinking
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Solution Overview
Problem
Conventional polyolefin-based thermoplastic elastomer compositions for airbag covers face challenges in achieving excellent low-temperature impact strength and tensile properties due to irregular chain cutting by organic peroxides and limitations in controlling crosslinking, leading to deteriorated physical properties and unintended deployment during airbag unfolding.
Innovation Solution
A polyolefin-based thermoplastic elastomer composition comprising a polypropylene-based resin, denatured polypropylene resin, ionomer resin, olefin-based copolymer elastomer, and styrene-based copolymer elastomer, which is partially crosslinked without using crosslinking agents, co-crosslinking agents, or free radical initiators, enhancing low-temperature impact strength and tensile properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If organic peroxide crosslinking is used to improve low-temperature impact strength, then crosslinking effect is achieved, but irregular chain cutting occurs causing molecular weight reduction and deteriorated physical properties
Solution Approach 1:
The patent removes organic peroxide crosslinking agents from the composition entirely, extracting the harmful crosslinking step that caused irregular chain cutting and molecular weight reduction, while achieving crosslinking through the intrinsic ionic interactions of ionomer resin instead
Solution Approach 2:
The patent changes the crosslinking mechanism from chemical crosslinking via organic peroxide to physical ionic crosslinking through ionomer resin, altering the fundamental parameter of how crosslinking is achieved to avoid harmful side effects
2Strength
If crosslinking agents and free radical initiators are used to enhance impact strength, then crosslinking network is formed, but crosslinking degree cannot be precisely controlled leading to unintended deployment
Solution Approach 1:
The ionomer resin self-crosslinks through its inherent ionic groups without requiring external crosslinking agents or free radical initiators, allowing precise control of crosslinking degree through composition design rather than complex chemical reactions
Solution Approach 2:
The ionomer resin acts as an intermediary that provides controlled ionic crosslinking between polymer chains, mediating the crosslinking process without the uncontrolled chemical reactions caused by free radical initiators
3Ease of manufacture
If thermoplastic elastomer is used to replace vulcanized rubber for simplified processing, then formability is improved, but low-temperature impact strength and tensile properties are insufficient
Solution Approach 1:
The patent creates a composite material system combining polypropylene-based resin with ionomer resin and elastomers, where the ionomer provides ionic crosslinking to enhance low-temperature impact strength while maintaining the thermoplastic nature for easy processing
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 composition exhibits improved low-temperature impact strength, tensile strength, and tensile elongation, ensuring accurate airbag deployment without fragment scattering, even under extreme temperature conditions, and maintains performance after thermal aging and thermal shock aging.
Implementation Method 1
the composition is partially crosslinked without using a crosslinking agent, a co-crosslinking agent or a free radical initiator
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
The present invention relates to a polyolefin-based thermoplastic elastomer composition for a vehicle airbag cover, including a polypropylene-based resin, a denatured polypropylene resin, an ionomer resin, an olefin-based copolymer elastomer and a styrene-based copolymer elastomer, an airbag cover material using the composition, and an airbag module using the airbag cover material.