Self-Sealing Elastomer Composition Manufacturing Process
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Solution Overview
Problem
Existing self-sealing compositions for tires face challenges in manufacturing due to high resin content, which affects hysteresis, rolling resistance, and cohesion, leading to issues like creep and undesirable adhesive bonding, especially when lacking sufficient filler.
Innovation Solution
A process for manufacturing a self-sealing composition using a masterbatch of solid unsaturated diene elastomer and hydrocarbon resin, with controlled hot compounding and incorporation of thiuram polysulphide, that reduces the need for liquid elastomer plasticizers and minimizes adhesive bonding, while maintaining puncture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high content of hydrocarbon resin is used in self-sealing composition, then self-sealing performance is improved, but rolling resistance increases and hysteresis deteriorates
Solution Approach 1:
The patent changes the molecular weight parameter of the elastomer to create a specific distribution (bimodal or multimodal) with both low and high molecular weight fractions. This parameter change allows the composition to achieve self-sealing performance with lower resin content, thereby reducing rolling resistance while maintaining the necessary sealing capability.
Solution Approach 2:
The patent uses a composite elastomer system combining different elastomer types (e.g., polybutadiene and styrene-butadiene copolymer) with specific molecular weight distributions. This composite approach enables synergistic effects where the low molecular weight fraction provides self-sealing properties while the high molecular weight fraction maintains structural integrity, reducing the need for high resin content.
2Reliability
If high content of hydrocarbon resin is used in self-sealing composition, then self-sealing performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-dissolving the elastomer in a specific solvent to create a uniform dispersion before compounding. This preliminary step simplifies the subsequent kneading process by ensuring homogeneous distribution of resin and elastomer, reducing the complexity of achieving proper mixing at high resin contents.
Solution Approach 2:
The patent introduces a specific solvent as an intermediary medium that facilitates the mixing of resin and elastomer. The solvent acts as a bridge, allowing the resin to be uniformly distributed throughout the elastomer matrix without requiring excessive mechanical energy input or complex kneading procedures.
3Ease of manufacture
If liquid elastomer is used to improve fluidity of composition, then processing ease is improved, but creep risk increases at high temperature
Solution Approach 1:
The patent changes the temperature parameter during processing to optimize the balance between fluidity and creep resistance. By controlling the processing temperature range and using thermal history effects, the composition achieves adequate fluidity for processing while maintaining structural stability during service, eliminating the need for liquid elastomer plasticizers.
Solution Approach 2:
The patent exploits the dynamic properties of the elastomer system, where the molecular weight distribution creates a viscoelastic response that adapts to different timescales. The low molecular weight fraction provides short-term fluidity for processing, while the high molecular weight fraction provides long-term structural stability, allowing the system to transition from processed state to service state without creep.
4Device complexity
If filler is omitted to simplify composition, then manufacturing simplicity is improved, but cohesion decreases leading to adhesive bonding
Solution Approach 1:
The patent employs the self-service principle where the elastomer system itself provides the necessary cohesion without external fillers. The specific molecular weight distribution and resin content are optimized so that the elastomer-resin matrix self-bonds through its own properties, eliminating the need for carbon black or other filler additives while maintaining adequate cohesion and preventing adhesive bonding to equipment.
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 process enables the production of a high-performance self-sealing composition with improved temperature stability, reduced creep, and enhanced cohesion, suitable for use in tires without increasing rolling resistance, and effectively seals punctures across a wide temperature range.
Implementation Method 1
mixing these various components in a mixer at a 'hot compounding' temperature or up to a 'hot compounding' temperature which is greater than the softening temperature of the hydrocarbon resin
Data Source
AI summary
Process for the manufacture of an elastomer composition having a self-sealing property which is based on at least (phr meaning parts by weight per 100 parts of solid elastomer): a solid unsaturated diene elastomer; between 30 and 90 phr of a hydrocarbon resin; from 0 to less than 30 phr of filler; between 0.5 and 15 phr of thiuram polysulphide, in which, during a first stage or stage (a), a masterbatch comprising at least the solid unsaturated diene elastomer and between 30 and 90 phr of a hydrocarbon resin is prepared by mixing these various components in a mixer at a “hot compounding” temperature or up to a “hot compounding” temperature which is greater than the softening temperature of the hydrocarbon resin.