Pneumatic Tire Inner Liner Composite Structure
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Solution Overview
Problem
Pneumatic tires face challenges in achieving improved air permeability resistance, reduced rolling resistance, and low temperature durability while maintaining weight reduction and simplicity in manufacturing, due to issues with adhesion and structural complexity in existing inner liner materials and designs.
Innovation Solution
A pneumatic tire with an inner liner composed of a polymer layer stack including a styrene-isobutylene-styrene triblock copolymer and a styrene-isoprene-styrene or styrene-isobutylene diblock copolymer, with a layered clay mineral and rubber components, arranged to vary in thickness to enhance adhesion and durability, and a specific thickness distribution to optimize weight reduction and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a thermoplastic resin is used for the inner liner to reduce weight, then weight reduction is achieved, but adhesive strength at the adhesion interface deteriorates due to shear strain
Solution Approach 1:
The patent employs a composite material structure consisting of a thermoplastic resin layer (for weight reduction and air permeability resistance) combined with a rubber layer (for adhesive strength). This multi-material approach allows the thermoplastic resin to provide weight reduction while the rubber layer compensates for insufficient adhesive strength at the adhesion interface, resolving the contradiction between weight reduction and adhesive strength maintenance.
2Weight of moving object
If the inner liner thickness is reduced to achieve weight reduction, then weight reduction is achieved, but air permeability resistance deteriorates
Solution Approach 1:
The patent uses a composite structure with a thermoplastic resin layer and a rubber layer, where each layer contributes different properties. The thermoplastic resin layer provides weight reduction, while the rubber layer enhances air permeability resistance. This composite approach allows the system to achieve weight reduction without sacrificing air permeability resistance, as the rubber layer compensates for the thinner overall structure.
3Weight of moving object
If the inner liner thickness is reduced to achieve weight reduction, then weight reduction is achieved, but strength and damage resistance deteriorate
Solution Approach 1:
The patent employs a composite material system where a thermoplastic resin layer is combined with a rubber layer. The thermoplastic resin provides weight reduction, while the rubber layer contributes superior strength and damage resistance. This composite structure allows the inner liner to be thinner overall while maintaining or enhancing strength characteristics through the rubber component.
4Strength
If adhesive layers are added to improve adhesion, then adhesive strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the adhesive function into the rubber layer itself, which inherently possesses adhesive properties due to its composition and interaction with the carcass ply. Instead of adding separate adhesive layers, the rubber layer serves dual purposes: providing structural strength and ensuring adhesion to the carcass ply. This integration simplifies the overall structure while maintaining necessary adhesive strength.
5Strength
If adhesive layers are added to improve adhesion, then adhesive strength is improved, but manufacturing steps and productivity deteriorate
Solution Approach 1:
The patent combines the adhesive function with the rubber layer, eliminating the need for separate adhesive application steps. The rubber layer's inherent adhesive properties allow it to bond directly with the carcass ply during the vulcanization process, integrating multiple functions into a single component and process step, thereby maintaining productivity while ensuring adequate adhesion.
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 solution provides improved air permeability resistance, reduced rolling resistance, and enhanced low temperature durability while maintaining weight reduction and simplifying the manufacturing process by increasing adhesive properties and structural integrity of the inner liner.
Implementation Method 1
a butyl rubber, is used... having favorable air permeability resistance
Implementation Method 2
improve adhesive property of an inner liner with a rubber layer adjacent thereto
Implementation Method 3
a vulcanization step... heated state in a vulcanization step
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
Provided is a pneumatic tire having improved air permeability resistance by improving adhesive property between an inner liner and a tire component adjacent thereto, reduced rolling resistance, and improved low temperature durability. The inner liner is composed of a polymer layer stack including a first layer containing an SIBS and a second layer containing at least one of an SIS and an SIB. At least one of the first layer and the second layer is a polymer composition containing one of a C4 polymer obtained by polymerizing a monomer unit having 4 carbon atoms, a layered clay mineral with an organic compound intercalated therein and at least one kind of rubber component selected from the group consisting of a natural rubber, an isoprene rubber and a butyl rubber. The second layer is arranged to come into contact with a rubber layer of the carcass ply. The inner liner has a thickness Ge at a shoulder position Pe exceeding 100% and being less than or equal to 500% of a thickness Gc at a crown central position Pc.