Thermoplastic Elastomer Composition for Welding Propylene Polymers
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Solution Overview
Problem
Existing thermoplastic elastomer compositions fail to provide molded bodies with adequate rigidity at high temperatures, impact strength at low temperatures, and welding strength, particularly when used in conjunction with propylene-based polymers.
Innovation Solution
A thermoplastic elastomer composition comprising specific components (A, B, C, and D) with defined weight ratios and properties, including a polymer with a high propylene monomer unit content, ethylene-propylene copolymers, and ethylene-α-olefin copolymers, which are melt-kneaded and used to create a composite molded body that can be welded with propylene-based polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thermoplastic elastomer composition containing a propylene-based polymer and an ethylene-propylene-based copolymer rubber is used, then the composition can be welded with a propylene-based polymer molded body, but the rigidity at high temperature, impact strength at low temperature, and welding strength are insufficient
Solution Approach 1:
The patent uses a composite material system consisting of four specific components: (A) a propylene-based polymer with intrinsic viscosity ≥1.05 dl/g, (B) an ethylene-propylene copolymer with intrinsic viscosity ≥5.5 dl/g, (C) an ethylene-α-olefin copolymer with specific composition ratios, and (D) another ethylene-α-olefin copolymer with different composition ratios. This multi-component composite approach allows simultaneous achievement of welding strength (through component A) and mechanical properties at extreme temperatures (through the synergistic combination of components B, C, and D with controlled viscosity and composition ratios).
Solution Approach 2:
The patent precisely controls multiple parameters including intrinsic viscosity values ([ηA]≥1.05 dl/g, [ηB]≥5.5 dl/g), composition ratios (ethylene content in copolymers), and weight percentages of each component (A: 26-59%, B: 2-9%, C: 16-61%, D: 11-56%). By optimizing these parameters, the composition achieves both adequate welding strength to propylene-based polymers and improved rigidity at high temperature and impact strength at low temperature.
2Temperature
If the content of propylene-based polymer is increased to improve rigidity at high temperature, then rigidity improves, but impact strength at low temperature and welding strength deteriorate
Solution Approach 1:
The patent assigns different functional roles to different components based on their local properties: Component (A) with high intrinsic viscosity provides welding strength and structural integrity; Component (B) with very high intrinsic viscosity (≥5.5 dl/g) provides impact strength at low temperatures; Components (C) and (D) with controlled ethylene content and viscosity ratios provide flexibility and low-temperature toughness. This functional differentiation allows the composition to exhibit appropriate properties at both high and low temperatures simultaneously.
Solution Approach 2:
The patent creates a multi-phase composite where Component (A) forms the continuous matrix providing high-temperature rigidity, while Components (B), (C), and (D) form dispersed phases providing impact strength at low temperatures. The specific viscosity ratios and composition ranges ensure proper phase distribution and interfacial adhesion, enabling the composite to maintain both rigidity at high temperature and toughness at low temperature.
3Strength
If the viscosity of the copolymer is increased to improve impact strength at low temperature, then impact strength improves, but processing difficulty and welding strength worsen
Solution Approach 1:
The patent divides the viscous copolymer function into two separate components: Component (B) with very high intrinsic viscosity (≥5.5 dl/g) that provides impact strength at low temperatures, and Component (C) with lower viscosity that ensures processability. This segmentation allows the high-viscosity component to be used in small amounts (2-9% by weight) to provide toughness without significantly affecting processing or welding, while the lower-viscosity components make up the bulk of the formulation.
Solution Approach 2:
The patent controls the intrinsic viscosity of Component (B) at a specific threshold (≥5.5 dl/g) and limits its content to 2-9% by weight. This parameter control ensures that enough high-viscosity material is present to provide impact strength at low temperatures, but not so much that it creates excessive processing difficulty or compromises welding strength. The viscosity of Component (C) is also controlled to balance processability and low-temperature flexibility.
Data Source
Figure 1~2
AI summary
A thermoplastic elastomer composition comprising components (A) to (D), wherein the content of the component (A), (B), (C) and (D) is, respectively, 26% by weight or more and 59% by weight or less, 2% by weight or more and 9% by weight or less, 16% by weight or more and 61% by weight or less and 11% by weight or more and 56% by weight or less, when the total amount of the components (A) to (D) is 100% by weight, and the ratio of the content of the component (C) to the content of the component (D) is over 1 and 5 or less.