Rubber Composition Inner Liner Air Permeability Fatigue
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Solution Overview
Problem
Rubber compositions for inner liners in tubeless pneumatic tires face challenges in achieving a balance between air permeability resistance and resistance to fatigue from flexing, particularly when using butyl type rubber and requiring the addition of softeners like process oil, which typically deteriorate air permeability resistance.
Innovation Solution
Incorporating carbon black and a modified silicone oil with silanol groups at the molecular terminal, which reacts with the carbon black, enhancing the polarity and preventing particle aggregation, thereby improving air permeability resistance and fatigue resistance while allowing the use of process oil without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flat-plate form filler is blended into rubber composition for inner liner, then air permeability resistance is improved, but resistance to fatigue from flexing is deteriorated
Solution Approach 1:
The patent introduces a silane coupling agent as an intermediary substance that mediates between the flat-plate form filler and the butyl rubber matrix. The coupling agent contains both inorganic filler surface groups and organic rubber-compatible groups, creating a bridge that improves interfacial adhesion. This resolves the contradiction by enabling the filler to maintain its air-blocking function while the coupling agent prevents stress concentration at the filler-rubber interface, thereby preserving fatigue resistance.
Solution Approach 2:
The patent creates a composite material system consisting of butyl rubber, flat-plate form filler, and silane coupling agent. This composite structure allows the filler particles to be uniformly distributed and well-bonded within the rubber matrix. The composite nature enables simultaneous achievement of high air permeability resistance (from the filler) and maintained fatigue resistance (from the improved interfacial bonding provided by the coupling agent).
2Ease of manufacture
If process oil is blended into rubber composition for inner liner, then workability is improved, but air permeability resistance is deteriorated
Solution Approach 1:
The patent changes the chemical parameters of the oil component by using specifically selected process oils with controlled molecular structures and polarities. By selecting process oils with appropriate chemical characteristics (such as aromatic content and molecular weight), the patent achieves optimal balance between workability enhancement and air permeability resistance maintenance. The parameter change involves selecting oils that provide sufficient plasticity without creating excessive free volume that would compromise airtightness.
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 rubber composition exhibits improved air permeability resistance and fatigue resistance, maintaining performance even when containing process oil, by utilizing the reactive properties of the modified silicone oil with carbon black, preventing nitrogen and oxygen dissolution and reducing particle aggregation.
Implementation Method 1
the modified silicone oil having a silanol group at a molecular terminal thereof can react with hydroxyl groups or carboxyl groups of the surface of the carbon black in the rubber composition
Implementation Method 2
the modified silicone oil having a silanol group at a molecular terminal thereof can react with hydroxyl groups or carboxyl groups of the surface of the carbon black
Data Source
AI summary
A rubber composition for an inner liner that has a carbon black and a modified silicone oil having a silanol group at a molecular terminal thereof can give a vulcanized rubber excellent in air permeability resistance and resistance to fatigue from flexing. This rubber composition can give a vulcanized rubber which can be restrained from being lowered in air permeability resistance and which is excellent in resistance to fatigue from flexing even when the rubber composition contains a process oil.