Pneumatic Tire Inner Liner Adhesion via Tackifier Composite
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Solution Overview
Problem
Current pneumatic tire inner liners face challenges in reducing crack growth due to flection deformation, maintaining internal pressure, and minimizing rolling resistance, particularly when using thinner thermoplastic resin or thermoplastic elastomer materials, which often result in poor adhesion and gas barrier properties.
Innovation Solution
A pneumatic tire design featuring a dual-layer inner liner composed of a first layer with a styrene-isobutylene-styrene block copolymer (SIBS) and a second layer with a styrene-isobutylene block copolymer, both containing tackifiers to enhance adhesion and durability, with specific thickness and molecular weight ranges to ensure optimal air permeability and adhesion strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a thermoplastic resin inner liner is used to reduce tire weight, then weight reduction is achieved, but the inner liner becomes too thin during vulcanization causing poor appearance and reduced gas barrier property
Solution Approach 1:
The patent uses a composite material consisting of thermoplastic elastomer base resin combined with specific tackifiers (petroleum resin, terpene resin, or phenolic resin) to create an inner liner that maintains adequate thickness while achieving the desired weight reduction. The composite formulation allows the inner liner to withstand vulcanization pressure without becoming excessively thin, thus preventing the 'open thread' phenomenon while still reducing tire weight compared to traditional butyl rubber liners.
2Weight of moving object
If the inner liner thickness is reduced to achieve weight reduction, then weight reduction is achieved, but gas barrier property deteriorates causing air leakage
Solution Approach 1:
The patent changes the chemical composition parameters of the inner liner material by incorporating specific tackifiers (petroleum resin with 40-70% aromatic hydrocarbons, terpene resin with 70-90% terpene components, or phenolic resin with 70-90% phenolic components) in controlled amounts (0.1-100 parts by mass relative to 100 parts by mass of thermoplastic elastomer). This compositional parameter change enables the thinner inner liner to maintain adequate gas barrier properties and air permeability resistance while still achieving weight reduction.
3Weight of moving object
If thermoplastic elastomer material is used to reduce inner liner thickness, then weight reduction is achieved, but vulcanization adhesion strength with carcass ply deteriorates
Solution Approach 1:
The patent creates a composite material system combining thermoplastic elastomer with specific tackifiers (petroleum resin, terpene resin, or phenolic resin) that enhances vulcanization adhesion strength. The tackifiers act as adhesion promoters that improve the bonding between the inner liner and the carcass ply rubber during vulcanization, compensating for the reduced thickness and preventing air-in phenomena while maintaining weight reduction benefits.
4Strength
If polyamide-based polymer is blended in SIBS to improve adhesion, then adhesion strength is improved, but flection cracking resistance deteriorates
Solution Approach 1:
The patent changes the material composition parameters by selecting specific tackifier types (petroleum resin, terpene resin, or phenolic resin) with controlled molecular structures and chemical compositions. These tackifiers provide adequate adhesion strength through their chemical properties (aromatic hydrocarbons, terpene components, or phenolic groups) without the adverse effects of polyamide-based polymers on flection cracking resistance. The patent maintains SIBS as the base resin to preserve flection cracking resistance while using the tackifiers to achieve the required adhesion strength.
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 dual-layer inner liner improves adhesion between layers and with the carcass ply, reducing air leakage, crack growth, and rolling resistance while maintaining excellent air permeability resistance, thus enhancing tire durability and fuel efficiency.
Implementation Method 1
A pneumatic tire design featuring a dual-layer inner liner composed of a first layer with a styrene-isobutylene-styrene block copolymer (SIBS) and a second layer with a styrene-isobutylene block copolymer, both containing tackifiers to enhance adhesion and durability
Implementation Method 2
the inner liner is thin, gas barrier property becomes partially bad to decrease tire internal pressure... The dual-layer inner liner improves adhesion between layers and with the carcass ply, reducing air leakage... while maintaining excellent air permeability resistance
Implementation Method 3
In addition to butylene, the rubber blend mainly containing the butyl rubber contains isoprene by approximately 1 mass %, which acts with sulfur, vulcanization accelerator, and zinc white to achieve cross-linking between rubber molecules
Data Source
Figure 1
Figure 2(a)~2(d)
AI summary
A pneumatic tire includes an inner liner disposed inwardly in the tire relative to a carcass ply bridged between a pair of bead portions, the inner liner being formed of a first layer disposed inwardly in the tire, and a second layer disposed in contact with a rubber layer of the carcass ply, the first layer being a thermoplastic elastomer composition mainly containing a styrene-isobutylene-styrene block copolymer, the second layer being a styrene-based thermoplastic elastomer composition, (a) at least one of the thermoplastic elastomer compositions of the first and second layers containing a tackifier by 0.1 part by mass to 100 parts by mass relative to 100 parts by mass of the thermoplastic elastomer, or (b) the second layer containing the styrene-isobutylene-styrene block copolymer by 10 mass % to 80 mass % relative to a thermoplastic elastomer component thereof.