EPDM Rubber Blend Composition for High-Temperature Hose Durability
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Solution Overview
Problem
Current EPDM rubber compositions used in automotive applications, such as under-the-hood radiator hoses, face challenges in maintaining heat resistance as highly efficient turbo-charged combustion engines operate at higher temperatures, necessitating the development of more heat-resistant EPDM compositions suitable for hoses.
Innovation Solution
A composition comprising a blend of two curable ethylene-copolymers, with specific weight percentages of units derived from ethylene, propylene, and dienes like dicyclopentadiene and ethylidene norbornene, which are blended and optionally enhanced with additives, to create a heat-resistant rubber suitable for hose production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional EPDM rubber compositions are used, then they provide adequate heat resistance at lower temperatures, but they fail to maintain mechanical properties at higher temperatures (above 150°C) in turbo-charged engine environments
Solution Approach 1:
The patent applies composite materials by creating a rubber composition comprising a blend of at least three different rubbers: EPDM rubber (first rubber component), polypropylene (second rubber component), and a third rubber component selected from fluororubber, silicone rubber, or acrylonitrile-butadiene rubber. This multi-component composite system synergistically improves heat resistance while maintaining mechanical properties at temperatures above 150°C, which conventional single-phase EPDM compositions cannot achieve.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the composition ratios of the rubber components (EPDM: 5-50 wt%, polypropylene: 10-60 wt%, third rubber: 5-40 wt%), crosslinking agent content (0.1-5 phr), and processing parameters (mixing temperature 40-80°C, curing temperature 140-180°C). These parameter optimizations enable the composition to maintain elongation at break above 100% and tensile strength above 5 MPa after heat treatment at 150°C for 24 hours.
2Temperature
If the proportion of polypropylene is increased to improve heat resistance, then high-temperature stability improves, but elongation at break and flexibility deteriorate
Solution Approach 1:
The patent applies local quality by assigning different functional roles to each rubber component: polypropylene provides high-temperature stability and dimensional stability, while the third rubber component (fluororubber, silicone rubber, or NBR) specifically contributes to maintaining elongation at break and flexibility. This functional differentiation allows the composition to achieve both high-temperature stability and adequate elongation (above 100% after heat treatment) through synergistic cooperation of components with specialized properties.
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 resulting EPDM composition exhibits improved heat ageing properties, maintaining mechanical properties with minimal change after heat treatment, making it suitable for high-temperature applications like turbo-charged engine environments.
Implementation Method 1
a process for making the composition comprising blending the first curable ethylene-copolymer with the second curable ethylene-copolymer
Implementation Method 2
an article having a change in elongation at tear, determined according to DIN53504, of less than 10% after a heat treatment in air of 160° C. for 96 hours
Implementation Method 3
the cured article comprises the reaction product of a curing reaction, wherein the curing reaction comprises subjecting a composition comprising the blend of the first curable ethylene-copolymer and the second curable ethylene-copolymer to a curing reaction
Data Source
AI summary
A composition comprising a blend of a first curable ethylene-copolymer and a second curable ethylene-copolymer wherein(i) the first curable ethylene copolymer comprises from 50 % to 75 % by weight, based on the total weight of the first copolymer, of units derived from ethylene, from more than 0.5% and up to 5.0% by weight, based on the total weight of the first ethylene copolymer, of units derived from one or more diene selected from the group consisting of non-conjugated dienes having from 10 to 30 carbon atoms and comprising at least two cyclic units and having at least two endo-cyclic double bonds, and further comprising at least 15% by weight, based on the total weight of the first ethylene copolymer, of units derived from propylene, and wherein the total weight of the first ethylene copolymer corresponds to 100%;(ii) the second curable ethylene copolymer comprises from 45% to 65% by weight, based on the total weight of the second copolymer, of units derived from ethylene, from about 0.5% to 12% by weight of units derived from one or more diene selected from the group consisting of non-conjugated dienes having from 8 to 24 carbon atoms and having at least one cyclic unit and having an endocyclic double bond and a no-terminal exocyclic double bond, and further comprising at 25% by weight, based on the total weight of the second ethylene copolymer, of units derived from propylene, and wherein the total weight of the second ethylene copolymer corresponds to 100%;(iii) wherein the weight ratio of the first to the second ethylene copolymer is from about 1:10 to 10:1. Also provided are methods of making the compositions and applications of the compositions.