Thermoplastic Elastomer Composition for PP Double-Injection Seals
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Solution Overview
Problem
Existing rubber seals for vehicle outside mirrors experience abnormal noise and abrasion due to friction with other components during folding and unfolding, and increasing slip agents to address these issues degrades double-injection properties and increases hardness and storage modulus.
Innovation Solution
A thermoplastic elastomer composition is formulated with a styrene-based thermoplastic elastomer, siloxane-based additive, amide-based slip agent, and thermoplastic vulcanizate, specifically using ethylene propylene diene monomer (EPDM) and polypropylene resin, to enhance double-injection properties, reduce hardness, and lower storage modulus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the slip agent is increased to reduce friction and prevent abrasion, then the abrasion resistance is improved, but the double-injection property with PP is degraded, hardness is increased, and the change of the storage modulus at the lower temperature is increased
Solution Approach 1:
The patent optimizes the slip agent content within a specific range (0.1-5 parts by weight per 100 parts of thermoplastic elastomer) to achieve the desired balance between abrasion resistance and double-injection properties. This parameter optimization resolves the contradiction by finding the precise dosage that provides sufficient friction reduction without excessive hardness increase or storage modulus change.
Solution Approach 2:
The patent creates a composite material system combining thermoplastic elastomer, thermoplastic vulcanizate, and slip agent. This composite approach allows the slip agent to be integrated into the material matrix, providing friction reduction while maintaining compatibility with polypropylene for double-injection molding and controlling the storage modulus characteristics.
2Object-generated harmful factors
If the slip agent is increased to reduce friction, then the friction coefficient is decreased, but the hardness is increased which leads to increased abrasion
Solution Approach 1:
The patent establishes an optimal slip agent concentration range (0.1-5 parts by weight per 100 parts of thermoplastic elastomer) that achieves sufficient friction reduction while preventing excessive hardness increase. This parameter control ensures the material remains soft enough to maintain good abrasion resistance while still providing the necessary lubrication effect.
Data Source
AI summary
A thermoplastic elastomer composition, which shows higher double-injection property with the PP, lower hardness, and the lower change in the storage modulus at the lower temperature, is prepared by mixing a proper content of a siloxane-based additive, a slip agent in a thermoplastic elastomer and a thermoplastic vulcanizate (TPV). The siloxane-based additive and slip agent are optimized to improve processability and mechanical properties, while the TPV component, including an ethylene propylene diene monomer (EPDM) and polypropylene resin, contributes to enhanced elasticity and stability. The formulation balances flexibility and strength, with siloxane additives improving surface characteristics and the slip agent reducing friction. The composition is suitable for various applications requiring robust elastomeric performance, especially in molded products where low-temperature resilience and high processability are critical. The overall polypropylene content is controlled to ensure optimal performance, not exceeding 5 wt %.