Thermoplastic Elastomer Composition for Low-Gloss Airbag Covers
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Solution Overview
Problem
Conventional thermoplastic elastomer compositions lack sufficient low-temperature impact resistance and exhibit undesirable luster on the tear line of unpainted airbag covers, affecting their appearance.
Innovation Solution
A thermoplastic elastomer composition comprising a propylene block copolymer, an ethylene/propylene/non-conjugated polyene copolymer, and an ethylene/α-olefin copolymer, subjected to dynamic heat treatment in the presence of a cross-linking agent, to enhance bending elasticity, low-temperature impact resistance, and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polyolefin resin and a polyester resin are used as a compatibilizer, then the processability is improved, but the tensile strength and elongation at break deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the compatibilizer from conventional polyolefin/polyester resins to a specific block copolymer structure (polyester block-polyurethane block-polyester block) with defined molecular weight ranges and soft segment content (30-70%). This parameter change resolves the contradiction by maintaining processability while preventing the deterioration of tensile strength and elongation at break that occurs with conventional compatibilizers.
2Ease of manufacture
If a polyolefin resin and a polyester resin are used as a compatibilizer, then the processability is improved, but the elongation at break deteriorates
Solution Approach 1:
The patent modifies the compatibilizer structure to include a polyurethane block with specific soft segment content (30-70% of total polyurethane block weight) and defined molecular weights. This parameter change enables the composition to maintain improved processability while preserving elongation at break properties, avoiding the deterioration that occurs with conventional polyolefin/polyester compatibilizers.
3Ease of manufacture
If conventional compatibilizers are used, then the mixing ease is improved, but the mechanical properties deteriorate
Solution Approach 1:
The patent employs a composite compatibilizer structure consisting of polyester blocks, polyurethane blocks with specific soft segments, and aromatic rings. This composite material approach enables both easy mixing (improved processability) and maintenance of superior mechanical properties, resolving the contradiction between mixing ease and mechanical property deterioration associated with conventional compatibilizers.
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 achieves excellent bending elasticity, low-temperature impact resistance, and appearance, effectively suppressing the luster of the tear line in unpainted airbag covers, resulting in a superior appearance.
Implementation Method 1
subjecting the following components: 41 to 70 parts by mass of component (A), 5 to 54 parts by mass of component (B), and 5 to 59 parts by mass of component (C) (provided that the total content of the components (A), (B), and (C) is 100 parts by mass) to dynamic heat treatment in a presence of a cross-linking agent
Data Source
Figure 1
AI summary
The present invention is a thermoplastic elastomer composition obtained by subjecting the following components: 41 to 70 parts by mass of component (A), 0 to 54 parts by mass of component (B), and 5 to 59 parts by mass of component (C) (provided that the total content of the components (A), (B), and (C) is 100 parts by mass) to dynamic heat treatment in the presence of a cross-linking agent. Component (A): a propylene block copolymer having a melt flow rate measured in accordance with ISO1133 at 230°C and a load of 2.16 kg of 20 g/10 min or more. Component (B): an ethylene/α-olefin/non-conjugated polyene copolymer including a structural unit derived from ethylene, a structural unit derived from an α-olefin having 3 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene. Component (C): an ethylene/α-olefin copolymer including a structural unit derived from ethylene and a structural unit derived from an α-olefin having 4 to 20 carbon atoms and having a melt flow rate measured in accordance with ISO 1133 at 190°C and a load of 2.16 kg of 5 g/10 min or less. The thermoplastic elastomer composition of the present invention has excellent bending elasticity, low-temperature impact resistance, and appearance, and in particular, it can suppress the luster of a tear line when molded into an unpainted airbag cover and can realize good appearance.