Microcapsule Vulcanization Accelerators for Tyre Rubber
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Solution Overview
Problem
Current rubber compound preparation processes face challenges in achieving homogeneous dispersion of the vulcanization system due to high viscosity during the productive mixing step, leading to premature vulcanization and productivity issues, as the vulcanization system must be added separately and dispersed over an extended period to avoid premature reaction.
Innovation Solution
Incorporating microcapsules made from a thermoplastic material with a melting temperature between 120 and 180°C and an average diameter of less than 1 µm, containing vulcanization accelerating agents, which are added during the non-productive mixing step, ensuring even dispersion without compromising productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vulcanization system is added during the productive mixing step to avoid premature vulcanization, then vulcanization control is improved, but the dispersion of the vulcanization system deteriorates due to high compound viscosity
Solution Approach 1:
The vulcanization system is segmented into two components: sulfur (added during non-productive mixing) and vulcanization accelerating agents enclosed in microcapsules (added during productive mixing). This segmentation allows sulfur to be incorporated when viscosity is lower for better dispersion, while the microencapsulated accelerators are added later when temperature control is critical, resolving the contradiction between dispersion quality and vulcanization control.
Solution Approach 2:
Microcapsules serve as an intermediary carrier for the vulcanization accelerating agents. These microcapsules protect the accelerators from premature reaction while enabling their controlled release during the productive mixing step. The microcapsule structure acts as a mediator that allows the accelerating agents to be added during temperature-sensitive mixing without triggering premature vulcanization, while still achieving adequate dispersion through the intermediary microcapsule form.
2Manufacturing precision
If the mixing period is prolonged to ensure correct dispersion of the vulcanization system, then dispersion quality is improved, but productivity deteriorates
Solution Approach 1:
The mixing process is segmented into two distinct phases: non-productive mixing (for incorporating sulfur at lower viscosity) and productive mixing (for incorporating microencapsulated accelerators). This segmentation allows each mixing phase to be optimized independently, reducing the need for prolonged mixing while ensuring proper dispersion of both sulfur and accelerating agents through their respective optimal mixing conditions.
Solution Approach 2:
The invention changes the physical state and size parameters of the vulcanization system components. Sulfur is used in its standard form added during low-viscosity mixing, while accelerating agents are encapsulated in microcapsules with average diameter of 1-10 μm. These parameter changes enable faster mixing rates and shorter mixing times while maintaining dispersion quality, as the microcapsulated accelerators disperse more readily than bulk accelerator materials.
3Productivity
If the compound temperature is raised to facilitate mixing, then mixing efficiency is improved, but premature vulcanization is triggered
Solution Approach 1:
The vulcanization accelerating agents are extracted from the main mixing process and enclosed in microcapsules that are added during the productive mixing step at controlled temperatures. This extraction allows the bulk mixing operations to proceed without the risk of premature vulcanization, as the accelerating agents are isolated within the microcapsule structure until the controlled addition point, separating the high-temperature mixing operations from the temperature-sensitive vulcanization chemistry.
Solution Approach 2:
The microcapsules act as an intermediary barrier between the compound and the vulcanization accelerating agents. This intermediary structure allows the compound to be mixed at temperatures that would normally trigger vulcanization without actually initiating the reaction, as the accelerating agents remain encapsulated and protected. The microcapsules mediate between the thermal conditions of mixing and the chemical sensitivity of the accelerators, enabling efficient mixing without premature vulcanization.
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 approach allows for effective dispersion of the vulcanization system, enhancing mechanical properties of the rubber compound and improving productivity by enabling the addition of sulfur during the initial mixing step, resulting in better mechanical characteristics and efficient vulcanization.
Implementation Method 1
microcapsules made from a thermoplastic material having a melting temperature between 120 and 180°C
Data Source
AI summary
A rubber compound for the preparation of parts of pneumatic tyres comprising at least one cross-linkable unsaturated chain polymer base, one reinforcing filler and one vulcanization system comprising, in turn, at least sulfur and vulcanization accelerating agents. The compound comprises microcapsules made from a thermoplastic material having a melting temperature of between 120 and 180°C and an average diameter of less than 1 µm. The microcapsules comprise the entirety of the vulcanization accelerating agents.