Ethylene-Diene Rubber Composition With Tuned Accelerator Ratio
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Solution Overview
Problem
Highly saturated diene elastomers used in tire rubber compositions vulcanize slowly, leading to longer press occupancy times and reduced productivity, while also being prone to bubble formation and inhomogeneity due to slower vulcanization kinetics, which affects tire endurance and cohesion.
Innovation Solution
A rubber composition comprising a highly saturated diene elastomer copolymer with at least 50% ethylene units, carbon black, and a vulcanization system with a mixture of sulfur and a primary and secondary accelerator, where the mass ratio of the secondary accelerator to the total accelerators is less than 0.7, optimizing the balance between vulcanization time and cohesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If highly saturated diene elastomers are used in rubber composition, then the rubber composition achieves good cohesive properties and resistance to crack propagation, but the vulcanization kinetics become slower resulting in longer press occupancy times and reduced productivity
Solution Approach 1:
The invention changes the chemical parameters of the vulcanization system by introducing a specific accelerator package (thiazole accelerator combined with guanidine or amine accelerator) and controlling sulfur content, which fundamentally alters the vulcanization kinetics of highly saturated diene elastomers, enabling fast curing while maintaining cohesive properties
Solution Approach 2:
The invention uses accelerator compounds (thiazole accelerators like MBT, MBTS and guanidine/amine accelerators) as intermediaries to mediate the vulcanization reaction between sulfur and highly saturated diene elastomer, facilitating faster crosslinking without compromising the cohesive structure
2Strength
If highly saturated diene elastomers are used in rubber composition, then the rubber composition achieves good cohesive properties, but the slower vulcanization kinetics allow bubble formation during continued cooking outside the press, reducing tire endurance
Solution Approach 1:
The invention modifies the vulcanization parameters by using a specific accelerator package that dramatically increases crosslinking speed, allowing the rubber composition to reach sufficient rigidity before leaving the press, thereby preventing bubble formation during subsequent cooking while maintaining cohesive properties
Solution Approach 2:
The invention performs preliminary vulcanization action within the press by using fast-acting accelerators that initiate and complete the majority of crosslinking before the rubber composition leaves the press, preventing later bubble formation during storage or mounting operations
3Reliability
If longer residence times in cooking presses are used to vulcanize highly saturated diene elastomers, then the rubber composition achieves sufficient rigidity to prevent bubble formation, but the production cycles are lengthened and productivity is reduced
Solution Approach 1:
The invention changes the kinetic parameters of vulcanization by introducing thiazole accelerators (MBT, MBTS) in combination with guanidine or amine accelerators, which fundamentally accelerates the crosslinking rate, allowing sufficient rigidity to be achieved in shorter press occupancy times and preventing bubble formation during extended cooking
Solution Approach 2:
The accelerator package acts as a catalyst intermediary that speeds up the vulcanization reaction between sulfur and highly saturated diene elastomer, enabling the rubber composition to reach the required rigidity state faster, thus preventing bubble formation without extending production cycles
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
This composition achieves faster vulcanization times without compromising cohesive properties, reducing the risk of bubble formation and enhancing tire durability, especially under heavy loads.
Implementation Method 1
the level of rigidity of a rubber composition is defined by the degree of vulcanization of the elastomer which depends on both the vulcanization kinetics and the residence time in the press
Implementation Method 2
WO 2014/114607 A1 describes tire rubber compositions based on carbon black and highly saturated diene elastomer
Data Source
AI summary
The present invention relates to a rubber composition which comprises at least 50 phr of a copolymer of ethylene and of 1,3-diene which contains at least 50 mol% of ethylene units, a carbon black and a vulcanization system comprising sulphur and a vulcanization accelerator which is a mixture of a primary accelerator and of a secondary accelerator; the weight ratio between the amount of the secondary accelerator and the total amount of accelerators is less than 0.7. Such a composition exhibits a good compromise between the cohesion and curing properties.