Thermoplastic Polyester Elastomer Composition for Thermal Aging Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thermoplastic polyester elastomer compositions face challenges in achieving a balance between thermal aging resistance and water resistance, particularly for car parts like engine components, where existing solutions either excel in one aspect but fall short in the other.
Innovation Solution
A thermoplastic polyester elastomer composition is developed, comprising a hard segment with aromatic dicarboxylic acid and aliphatic diol, a soft segment with aliphatic polyether, a modified hydrogenated styrene-type elastomer, a carbodiimide compound, and antioxidants, which provides excellent thermal aging and water resistance by maintaining tensile elongation retention after thermal and hydrolytic treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyoxyalkylene glycol (polyether type) is used as soft segment, then water resistance and low-temperature characteristics are improved, but thermal aging resistance deteriorates
Solution Approach 1:
The patent changes the chemical structure parameter of the soft segment from polyether type to polyester type (specifically using PCL or PBA), which fundamentally alters the material's resistance characteristics. This structural parameter change enables the elastomer to achieve both good water resistance and improved thermal aging resistance compared to conventional polyether-based elastomers.
Solution Approach 2:
The patent creates a composite elastomer system by combining polyester-based hard segments (PBT or PBN) with polyester-based soft segments (PCL or PBA) in specific ratios. This composite structure allows the material to exhibit both the thermal aging resistance of polyester and the flexibility required for elastomeric performance, while achieving balanced water resistance.
2Temperature
If polyester is used as soft segment, then thermal aging resistance is improved, but water resistance and low-temperature characteristics deteriorate
Solution Approach 1:
The patent optimizes the molecular weight parameter of the polyester soft segment within the range of 5,000-50,000, and controls the soft segment content at 30-70 parts by mass per 100 parts of hard segment. These parameter optimizations ensure that the polyester soft segment provides thermal aging resistance while maintaining adequate water resistance through controlled crystallinity and phase separation.
Solution Approach 2:
The patent creates local quality differentiation within the elastomer structure by forming distinct hard segments (PBT/PBN) and soft segments (PCL/PBA) that phase-separate into different regions. The hard segments provide thermal stability and structural integrity, while the soft segments provide flexibility and contribute to water resistance through their specific polyester structure, achieving localized functional optimization.
3Temperature
If conventional antioxidant packages are added to polyester elastomer, then thermal aging resistance is partially improved, but hydrolysis resistance remains insufficient
Solution Approach 1:
The patent converts the inherent susceptibility of polyester to hydrolysis into a benefit by carefully selecting polyester soft segments with specific molecular weights and structures (PCL or PBA) that exhibit lower hydrolytic instability but provide adequate flexibility. The controlled phase separation and crystallinity in the composite structure actually protect the polyester chains from water attack, transforming the potential weakness into a balanced performance characteristic.
Solution Approach 2:
The patent changes the chemical composition parameters by selecting specific polyester types (PCL or PBA) with controlled molecular weights (5,000-50,000) and optimizing the ratio of soft to hard segments (30-70 parts per 100 parts). These parameter changes create a molecular structure that inherently resists hydrolysis while maintaining thermal aging resistance, eliminating the need for extensive antioxidant packages.
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 enhanced flexibility, thermal aging resistance, and water resistance, making it suitable for critical engine parts such as air ducts, resonators, and air cleaners, with improved retention rates of tensile elongation after thermal and hydrolytic stress.
Implementation Method 1
0.1 to 10 part(s) by mass of a carbodiimide compound (C)... a retention rate (%) of tensile elongation at break of the molded product after a thermal treatment at 150° C. for 250 hours is 70% or more, and a retention rate (%) of tensile elongation at break of the molded product after a treatment with boiling water of 100° C. for 350 hours is 60% or more
Implementation Method 2
0.01 to 5 part(s) by mass of an antioxidant of a hindered phenol type (D)... thermal aging resistance
Implementation Method 3
0.01 to 5 part(s) by mass of an antioxidant of a sulfur type (E)... thermal aging resistance
Data Source
AI summary
The present invention provides a thermoplastic polyester elastomer composition which is flexible and exhibits excellent thermal aging resistance and water resistance. According to the present invention, there is provided a thermoplastic polyester elastomer composition wherein, to 100 parts by mass in total of a thermoplastic polyester elastomer (A) and a modified hydrogenated styrene-type elastomer (B), 0.1 to 10 part (s) by mass of a carbodiimide compound (C), 0.01 to 5 part (s) by mass of an antioxidant of a hindered phenol type (D) and 0.01 to 5 part (s) by mass of an antioxidant of a sulfur type (E) are contained, wherein the thermoplastic polyester elastomer (A) comprises a hard segment comprising a polyester constituted from an aromatic dicarboxylic acid and an aliphatic diol or an alicyclic diol and a soft segment comprising an aliphatic polyether as main constituent ingredients, wherein a content of the soft segment is 3 to 40% by mass, wherein a rate by mass of the above (A) to the above (B) ((A)/(B)) is from 95/5 to 40/60.