High-Silica Rubber Composition for Stable Extrusion Aging
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Solution Overview
Problem
High silica rubber compositions exhibit significant variability in green rubber properties such as die swell and surface roughness, limiting their use in extrusion processes and affecting tire manufacturing efficiency and quality.
Innovation Solution
The use of disulfide silanes in rubber mixtures, particularly bis(triethoxysilylpropyl)disulfide, improves green rubber properties by reducing die swell and surface roughness, allowing for smoother extrusion and better age tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polysulfide silanes are used to bond silica filler to rubber compound, then bonding strength is improved, but green rubber properties become unstable with significant variability in viscosity, die swell, and surface roughness during aging
Solution Approach 1:
The patent changes the chemical structure of the silane coupling agent from polysulfide to disulfide, altering the bonding mechanism between silica filler and rubber compound. This parameter change in the coupling agent structure resolves the contradiction by providing both strong bonding and stable green rubber properties during aging, eliminating the variability issues with viscosity, die swell, and surface roughness.
2Strength
If conventional silane coupling agents are used, then silica-rubber bonding is improved, but die swell and surface roughness increase during storage and aging
Solution Approach 1:
The patent modifies the silane coupling agent structure by replacing polysulfide groups with disulfide groups. This structural parameter change maintains strong silica-rubber bonding while significantly reducing die swell and surface roughness during storage and aging, thereby improving manufacturing precision in extrusion processes.
3Manufacturing precision
If extrusion speed is reduced to control die swell and surface roughness, then green rubber quality improves, but production productivity decreases
Solution Approach 1:
The patent changes the chemical composition of the rubber compound by using disulfide silane instead of polysulfide silane. This parameter change in the compound formulation allows extrusion at normal speeds while maintaining excellent surface finish and minimal die swell, thus preserving both extrudate quality and production productivity without the need to reduce extrusion speed.
4Manufacturing precision
If processing aids are added to control die swell and surface roughness, then extrusion quality improves, but final product physical properties are adversely affected
Solution Approach 1:
The patent modifies the fundamental chemical structure of the silane coupling agent from polysulfide to disulfide type. This parameter change eliminates the need for additional processing aids by inherently providing controlled die swell and smooth surface finish, thereby maintaining both extrusion quality and the physical properties of the final vulcanized product without compromise.
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
Disulfide silanes enhance the processability of high silica rubber compositions by maintaining smooth surfaces and minimal die swell over time, enabling efficient storage and further processing without adverse aging effects.
Implementation Method 1
The silane coupling agent has three fundamental functions in silica mixes: cover the silica and hide the highly polar silanol groups from the hydrophobic elastomer, provide a chemical link between the silica and the elastomer, and adjust the curing of the silica mix.
Implementation Method 2
Silane is a well-known coupling agent used to increase the bonding of the silica filler to the rubber compound.
Implementation Method 3
mixed in a first mixer then passed through a pair of cylinders for forming a rubber sheet, cooled, and mixed in a second mixer
Data Source
AI summary
An improved rubber composition process having improved extrudate properties and exhibiting superior tolerance to aging when subject to multi-step mixing process and in particular to a mixing process where the rubber composition is mixed in a first mixer, cooled by passing between a pair of cylinders, then mixed in a second mixer, the composition comprised of a disulfide silane.