EPDM Rubber Blend Composition for High-Temperature Hose Ageing
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Solution Overview
Problem
There is a need for EPDM rubber compositions that are more heat-resistant than existing ones, particularly for use in under-the-hood radiator hoses in the automotive industry, where highly efficient turbo-charged engines generate higher temperatures than their predecessors, necessitating improved heat ageing properties.
Innovation Solution
A composition is developed comprising a blend of two curable ethylene-copolymers, one with 50-75% ethylene and 15% propylene, and another with 45-65% ethylene and 25% propylene, along with specific diene units, which are blended in a weight ratio of 1:10 to 10:1 and optionally include additives, to enhance heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional EPDM compositions are used, then they provide adequate heat resistance at lower temperatures, but they fail to maintain mechanical properties at higher temperatures generated by turbo-charged engines
Solution Approach 1:
The invention uses a composite material system consisting of two different curable ethylene-copolymer rubbers with distinct compositional characteristics. The first rubber contains 50-75% ethylene, 15-35% propylene and 5-20% non-conjugated diene, while the second rubber contains 45-65% ethylene, 25-40% propylene and 1-10% non-conjugated diene. This composite approach allows the blend to achieve superior heat resistance at high temperatures while maintaining mechanical property retention, resolving the contradiction between temperature resistance and reliability.
2Temperature
If the ethylene content is increased to improve heat resistance, then temperature tolerance improves, but the composition becomes less versatile for different application requirements
Solution Approach 1:
The invention applies local quality by creating two distinct rubber compositions with different local compositional characteristics. The first rubber has higher ethylene content (50-75%) for heat resistance, while the second rubber has higher propylene content (25-40%) for maintaining mechanical properties. By blending these two locally optimized compositions, the system achieves both heat resistance and compositional flexibility for different applications.
3Ease of manufacture
If a single curable ethylene-copolymer is used, then the composition is simple to manufacture, but it cannot achieve the desired heat ageing properties
Solution Approach 1:
The invention uses a composite material system consisting of two different curable ethylene-copolymer rubbers with distinct compositional characteristics. The first rubber contains 50-75% ethylene, 15-35% propylene and 5-20% non-conjugated diene, while the second rubber contains 45-65% ethylene, 25-40% propylene and 1-10% non-conjugated diene. This composite approach allows the blend to achieve superior heat resistance at high temperatures while maintaining mechanical property retention, resolving the contradiction between temperature resistance and reliability.
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.