Elastomer Nanocomposites for Tire Innerliner Air Retention
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Solution Overview
Problem
Existing nanocomposites used in tire innerliners face challenges in achieving effective dispersion and exfoliation of clays due to their hydrophobic and polymeric nature, leading to suboptimal air retention and processability.
Innovation Solution
A method involving the use of functionalized poly(isobutylene-co-p-methylstyrene) elastomer and layered fillers, with the elastomer and fillers dispersed in separate solvents and combined with processing aids to form a nanocomposite, which is then precipitated and dried to enhance air retention and processability, while eliminating naphthenic oils to improve impermeability and maintain compound processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nanocomposites are made by melt mixing elastomers and clay at elevated temperature, then the processing is simplified, but the dispersion and exfoliation of clays is poor due to hydrophobic and polymeric nature of butyl rubber
Solution Approach 1:
The patent changes the processing parameters from melt mixing to solution processing at lower temperatures. The elastomer and clay are dissolved/dispersed in a solvent (e.g., toluene, xylene, or THF) at temperatures below the elastomer's glass transition temperature, allowing for better clay exfoliation and dispersion while maintaining processing feasibility. After processing, the solvent is removed to obtain the nanocomposite.
Solution Approach 2:
The patent introduces a solvent as an intermediary medium to facilitate the interaction between hydrophobic butyl rubber and hydrophilic clay. The solvent acts as a bridge that enables proper dispersion and exfoliation of clay layers within the elastomer matrix, overcoming the inherent incompatibility between these materials.
2Ease of operation
If naphthenic oils are added to innerliner formulation to ensure adequate processing quality, then processability is improved, but impermeability performance deteriorates
Solution Approach 1:
The patent changes the processing conditions to lower temperatures (below the elastomer's glass transition temperature) and uses solution processing instead of conventional high-temperature mixing. This allows for adequate compound processability without requiring excessive naphthenic oils, thereby maintaining the impermeability and air retention properties of the butyl rubber elastomer.
3Ease of manufacture
If conventional melt mixing is used to form nanocomposites, then processing is straightforward, but the air retention properties are suboptimal due to poor clay exfoliation
Solution Approach 1:
The patent employs solution processing at lower temperatures with extended mixing times to achieve thorough clay exfoliation and dispersion. This method produces superior nanocomposites with enhanced air retention properties compared to conventional melt mixing, while the solvent removal step simplifies the overall process.
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 method results in improved air retention and processability of tire innerliners with a reduced permeation coefficient, achieving enhanced impermeability and weight savings in tire construction.
Implementation Method 1
the functionalized poly(isobutylene-co-p-methylstyrene) elastomer is dispersed in a first solvent to form a first solvent mixture, and separately, the one or more layered fillers is dispersed in a second solvent to form a second solvent mixture
Implementation Method 2
precipitating the nanocomposite composition
Data Source
AI summary
This disclosure is directed to nanocomposite compositions that are suitable for air bladders, innertubes, innerliners and other desirable air-retention articles. In particular, this disclosure is directed to compositions that include the nanocomposite, the nanocomposite made in such that its air-retention properties are much improved over what is known, while maintaining desirable elasticity and processability. In a particular aspect, an air-retention article such as an innerliner if formed by first contacting a desirable elastomer, especially a functionalized poly(isobutylene-co-p-methylstyrene) elastomer, with one or more layered fillers such as a clay described further below, and also contacting one or more processing aids, and one or more solvents to form an nanocomposite composition. The nanocomposite composition is then precipitated to form the solid nanocomposite composition which can be dried and further blended with other suitable ingredients such as, for example, curative agents, thus forming an innerliner suitable for a tire or other article.