Run-Flat Tire Carcass Cord Adhesion for Heat Fatigue Resistance
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Solution Overview
Problem
Safety tires with side reinforcement face challenges in maintaining durability and adhesive strength between polyester or aramid fibers and rubber, especially under high-load and high-temperature conditions, leading to decreased cord strength and fatigue.
Innovation Solution
A pneumatic safety tire design with a carcass ply composed of polyester or aramid fibers treated with a specific adhesive agent combination, including thermoplastic polymers, heat reactive aqueous urethane resin, and epoxide compounds, and a resorcin-formalin-latex-based adhesive, optimized by specific area ratios of side reinforcing rubber, bead filler, and rubber chafer to enhance rigidity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyester fiber or aramid fiber is used as a carcass ply cord and treated with conventional adhesive agents, then the adhesive strength between the cord and rubber is improved, but under high-load and high-temperature conditions, the adhesive strength decreases and cord fatigue occurs
Solution Approach 1:
The patent uses a composite adhesive agent system combining multiple components: (A) thermoplastic polymer with carboxyl groups, (B) polyisocyanate compound, and optionally (C) silane compound. This composite approach creates synergistic effects where each component contributes different properties - the thermoplastic polymer provides base adhesion, the polyisocyanate enhances chemical bonding, and the silane compound adds heat resistance through cross-linking reactions. This multi-component composite adhesive system resolves the contradiction by maintaining strong adhesion at elevated temperatures where single-component adhesives fail.
Solution Approach 2:
The patent specifies precise parameter ranges for the adhesive agent components to optimize performance: the thermoplastic polymer has carboxyl content of 0.01-5 mmol/g, the polyisocyanate compound is present at 1-50 parts by mass per 100 parts of thermoplastic polymer, and the silane compound (when used) is present at 1-50 parts by mass per 100 parts of thermoplastic polymer. These controlled parameter changes ensure the adhesive agent maintains optimal bonding strength and heat resistance, preventing cord fatigue under high-load conditions while achieving strong initial adhesion.
2Reliability
If the side reinforcing rubber area is increased to improve run-flat performance, then the tire can maintain load support at low pressure, but the compression strain on the carcass ply cord increases causing fatigue
Solution Approach 1:
The patent applies local quality by creating a side reinforcing rubber layer with specific geometric characteristics (crescent cross-section) positioned at the lower side wall portion of the tire. This localized reinforcement provides the necessary structural support for run-flat performance specifically where needed (at the bead area and lower sidewall) without uniformly increasing rubber thickness throughout the entire tire, thereby minimizing unnecessary compression strain on the carcass ply cord in other regions.
Solution Approach 2:
The side reinforcing rubber layer is pre-positioned in the lower side wall portion before the tire experiences run-flat conditions. This preliminary structural preparation ensures that when pressure loss occurs, the reinforcement is already in place to support the load and distribute stresses, preventing excessive compression strain on the cord during the actual run-flat operation rather than allowing damage to occur and then compensating.
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 tire exhibits improved durability and heat-resistant adhesive properties, maintaining strength and reducing fatigue, allowing for longer travel distances at low inner pressure.
Implementation Method 1
an adhesive agent treatment in which an adhesive agent containing at least one of a thermoplastic polymer (A), a heat reactive aqueous urethane resin (B), and an epoxide compound (C) is used as a first bath treatment liquid, and a resorcin-formalin-latex-based adhesive agent is used as a second bath treatment liquid
Data Source
Figure 1(a)~1(c)
Figure 2~4
Figure 5~6
AI summary
Provided is a pneumatic safety tire in which the durability is improved by improving the compression fatigue property of a carcass ply cord. The pneumatic safety tire includes, as a skeleton, a carcass, and a side reinforcing rubber. Provided that the area of the side reinforcing rubber is S1, the area of a bead filler is S2, and the area of a rubber chafer is S3, the following expressions (1) and (2) are satisfied: a reinforcing cord of a carcass ply is composed of a polyester fiber and/or an aramid fiber, and subjected to an adhesive agent treatment in which an adhesive agent containing at least one of a thermoplastic polymer, a heat reactive aqueous urethane resin, and an epoxide compound is used for a first bath, an RFL-based adhesive agent is used for a second bath, and a principal chain of the thermoplastic polymer substantially fails to include a double bond between carbons having an addition reactivity, is composed of an ethylene addition polymer and/or a urethane-based high molecular weight polymer, each of which is composed mostly of a linear chain structure, and includes a cross-linkable functional group as a pendant group.